feat: Sharable testimonials models

[archx3]

Summary / Highlights

This pull request introduces a new testimonial sharing settings model to manage the automatic sharing of testimonials across various communities. Additionally, it adds new enums for location and sharing types to support these sharing settings. The existing models were updated to accommodate new fields related to the sharing type and the communities where testimonials are shared.

Details (Give details about what this PR accomplishes, include any screenshots etc)

Testing Steps (Provide details on how your changes can be tested)

Requirements (place an x in each [ ])

• [ ] I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• [ ] I've tested my changes manually.
• [ ] I've added unit tests to my PR.

Transparency (Project board)

• [ ] I've given my PR a meaningful title.
• [ ] I linked this PR to the relevant issue.
• [ ] I moved the linked issue from the "Sprint backlog" to "In progress" when I started this.
• [ ] I moved the linked issue to "QA Verification" now that it is ready to merge.