Closes #9547
Addresses main issue where the text in the workspaces search bar would periodically get garbled, especially if you kept typing very fast.

Changes made

• Replaced debounce-it usage for the page with a home-spun useDebouncedFunction
  • The library's debounce utility assumes it's called in regular JavaScript, so it kept creating a brand new stateful function on every single render. That was splitting up all the debounced calls, instead of having them go to one centralized place
  • There are still other parts of the codebase that need to have this swap made; will open a new issue shortly about getting those areas updated (changes were out of scope for this PR)
  • Hook has tests in place, too, just to give us more confidence when we use it in the future.
• Reorganized some of the code and also added a few extra checks to minimize risks of accidental state desyncs between the search bar state and the global query state that it's based off of

Other notes

• Accidentally got confused when I was learning the codebase (lowercase filter.tsx vs uppercase Filter.tsx), and refactored a file that didn't really need changes. Functionality is the same; it was a pure refactor.
  • Will be more dutiful about making sure PRs don't touch any unnecessary files in the future