Add component date field manipulation example

[castroalves]

Problem Description

A customer would like to order content by date. However, the date field is under a modular component, which doesn't support order by right now.

Solution

This is a PoC that uses the app framework to create a custom date field UIX, that can be added to any model at the top level. Its values changes whenever a user picks a date under a modular component.

Keep in mind that it's a workaround. So if you interact with the data via api you are responsible for filling both fields in sync.

Obs.: It has been created for a very specific use case. If one would like to use it, the could should be changed, as field names are hardcoded.

[jpedroschmitz]

I think the only thing that requires change is the readme. Check this example:
https://github.com/hygraph/hygraph-examples/tree/master/with-apollo-client-3

We only need to follow the pattern, but other than that, all good 🙌🏻