feat: add data attributes definition for learning subdomain

[mariajgrimaldi]

Description:
This PR adds class definitions for the objects that will be sent by Open edX events, they are based in the library

JIRA:
https://edunext.atlassian.net/browse/PS2021-629?atlOrigin=eyJpIjoiODIwNDA5M2MxZGRlNGQ2NjhjNjJhZWIwNWZiNWNlYjUiLCJwIjoiaiJ9

Dependencies:
This PR depends on #7. Merged already

Testing instructions:
In your Open edX devstack

1. Go to lms shell make lms-shell
2. Install openedx-events specifying the events definition branch:
   pip install git+https://github.com/eduNEXT/openedx-events.git@MJG/event_data#egg=event_data
3. Go to the lms Django shell: python manage.py lms shell
4. Now, you can import the platform objects and map them to attrs classes. For example, you could do:

>>> from common.djangoapps.student.models import CourseEnrollment
>>> from openedx_events.learning.data import CourseEnrollmentData, UserData, UserPersonalData, CourseOverviewData
>>> course_enrollment = CourseEnrollment.objects.get(id=1)

*** MAPPING CourseEnrollment to CourseEnrollmentData ***
>>> course_enrollment_data = CourseEnrollmentData(
...                             user=UserData(
...                                 user_pii=(
...                                       username=course_enrollment.user.username,
...                                       email=course_enrollment.user.email,
...                                       name=course_enrollment.user.profile.name                                 
...                                  ),
...                                  id=course_enrollment,ent.user.id,
...                                  is_active=course_enrollment.user.is_active
...                             ),
...                             course=CourseOverviewData(
...                                 course_key=course_enrollment.course.id,
...                                 display_name=course_enrollment.course.display_name
...                             ),
...                             mode=course_enrollment.mode,
...                             creation_date=course_enrollment.created,
...                             is_active=course_enrollment.is_active
...                         )
>>> print(course_enrollment_data)
>>> import attr
>>> attr.asdict(course_enrollment_data)

Reviewers:

• tag reviewer
• tag reviewer

Merge checklist:

• All reviewers approved
• CI build is green
• Version bumped
• Changelog record added
• Documentation updated (not only docstrings)
• Commits are squashed

Post merge:

• Create a tag
• Check new version is pushed to PyPI after tag-triggered build is
  finished.
• Delete working branch (if not needed anymore)

Author concerns: List any concerns about this PR - inelegant
solutions, hacks, quick-and-dirty implementations, concerns about
migrations, etc.
Description:
This PR adds class definitions for the objects that will be sent by Open edX events, they are based in the library

JIRA:
https://edunext.atlassian.net/browse/PS2021-629?atlOrigin=eyJpIjoiODIwNDA5M2MxZGRlNGQ2NjhjNjJhZWIwNWZiNWNlYjUiLCJwIjoiaiJ9

Dependencies:
This PR depends on #7

Testing instructions:
In your Open edX devstack

1. Go to lms shell make lms-shell
2. Install openedx-events specifying the events definition branch:
   pip install git+https://github.com/eduNEXT/openedx-events.git@MJG/event_data#egg=event_data
3. Go to the lms Django shell: python manage.py lms shell
4. Now, you can import the platform objects and map them to attrs classes. For example, you could do:

>>> from common.djangoapps.student.models import CourseEnrollment
>>> from openedx_events.learning.data import CourseEnrollmentData, UserData, UserPersonalData, CourseOverviewData
>>> course_enrollment = CourseEnrollment.objects.get(id=1)

*** MAPPING CourseEnrollment to CourseEnrollmentData ***
>>> course_enrollment_data = CourseEnrollmentData(
...                             user=UserData(
...                                 user_pii=(
...                                       username=course_enrollment.user.username,
...                                       email=course_enrollment.user.email,
...                                       name=course_enrollment.user.profile.name                                 
...                                  ),
...                                 id=course_enrollment,ent.user.id,
...                                 is_active=course_enrollment.user.is_active
...                             ),
...                             course=CourseOverviewData(
...                                 course_key=course_enrollment.course.id,
...                                 display_name=course_enrollment.course.display_name
...                             ),
...                             mode=course_enrollment.mode,
...                             creation_date=course_enrollment.created,
...                             is_active=course_enrollment.is_active
...                         )
>>> print(course_enrollment_data)
>>> import attr
>>> attr.asdict(course_enrollment_data)

Reviewers:

• @felipemontoya

Merge checklist:

• All reviewers approved
• CI build is green
• Version bumped
• Changelog record added
• Documentation updated (not only docstrings)
• Commits are squashed

Post merge:

• Create a tag
• Check new version is pushed to PyPI after tag-triggered build is
  finished.
• Delete working branch (if not needed anymore)

[mariajgrimaldi]

This PR was opened because #8 was a PR to an intermediate branch. Please, refer to #8 for design discussions.

[mariajgrimaldi]

Hey @felipemontoya, thanks for the recommendation! Do you think we are ready to merge?

[felipemontoya]

I think we are

[felipemontoya]

Good work, we are ready to merge this and focus on the usage now.

Btw, the example of code in the cover letter is now outdated.