Error tracking client keys api

What does this MR do?

Adds error tracking client keys API endpoints.

Some background:

1. Client keys were introduced in !66466 (merged) as part of new feature development.
2. Client keys are needed to authenticate requests from user apps reporting errors to our collector.
3. This is all part of big feature: integrated error tracking. Its alternative to Sentry backend. #329596 (closed)
4. Integrated error tracking is behind a disabled feature flag.

With this merge request merged, I will be able to create a client keys via API on staging and prod and tests the whole error tracking feature.

Issue #329596 (closed)

How to setup and validate locally (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
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• [-] I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• [-] I have tested this MR in all supported browsers, or it's not needed.
• [-] I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.