Add in README `OpenSSF scorecard`

[B3nz01d]

Description

As a user of the OUDS library
I want to be able to view the OpenSSF Scorecard
So that I can assess the security level of the library according to their criteria even if some of them are not applicable

Context

As it was done on OUDS-iOS, a scorecard should be calculated automatically and added as a badge in the GitHub README.
This is required for Federation IT.

Definition of Done

• Display the badge in the README
• Add an hyperlink redirecting to the report when click on the badge
• If some criterias can be applied ot increase the score, do them, otherwise created dedicated issues

Notes

• A GitHub Actions workflow should be created
• Some privileges should be given to the repository; if needed or blocked contact Orange-OpenSource admins as usual
• Follow the documentation with instructions

Resources

• Best practices of OpenSSF
• Introduction to OpenSSF Scorecard
• Web page of OpenSSF scorecard with instructions to follow
• OUDS iOS README reference
• OUDS iOS generated report
• OUDS iOS GitHub Actions workflow