Hide resolve thread button from guest

Issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/66842

What does this MR do?

Since non member can't resolve a thread, a better UI experience is to hide that button from them.

If current user is a guest, the resolve thread group button is gone:

If current user is a member, the resolve thread group button still exists:

Test Case

Setup

1. Create a new public group
2. Create a new public project
3. Create a new merge request

Administrator

• As an Administrator, write a comment and click the start thread button
• Find that thread comment
• The "Resolved thread" button exists

Guest

• Impersonate a guest
• Find a thread that the administrator left
• Reply and click "Comment" button
• The "Resolve thread" button does not exist

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry for user-facing changes, or community contribution. Check the link for other scenarios.
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Closes #62122 (moved)