[FE] Introduce not filters for code review analytics
This MR adds negative filter options for code review analytics.
The BE has been implemented in !30506 (merged).
Note: With the changes introduced in this MR, we'll be able to support not filters for both the legacy filtered search and the new GlFilteredSearch component which is still behind the code_review_analytics_has_new_search feature flag.
Closes #206955 (closed)
Screenshots
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Edited by Martin Wortschack