Service for calling Sentry issues api

What does this MR do?

This MR is one of many for implementing listing of sentry issues in GitLab.

This MR contains the SentryIssueService which will call the sentry API to get the list of issues.

The target branch for this MR is 55178-db_and_model, which is the branch containing the DB migration and ErrorTrackingSetting model.

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/55178

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer