[Issue #31] Update repo with working title

[widal001]

Summary

Updates the repository to adopt the working title for the protocol: "CommonGrants"

• Fixes [Branding] Choose a working title for the protocol #31
• Time to review: 5 minutes

Changes proposed

What was added, updated, or removed in this PR.

• Updates the TypeSpec library and example API to use CommonGrants instead of OpportunityStream
• Updates and expands the READMEs to link to these sections of the codebase

Context for reviewers

Testing instructions, background context, more in-depth details of the implementation, and anything else you'd like to call out or ask reviewers. Explain how the changes were verified.

A lot of files were changed but the changes themselves are relatively minor.

Additional information

Screenshots, GIF demos, code examples or output to help show the changes working as expected.