Add reusable SearchInput component and docs

[krowvin]

Summary

Adds a reusable SearchInput component to groundwork-water so district sites can share the
same search bar behavior without copying app-specific Redux/search code.

What changed

• added SearchInput to the library export
• built in debounced query handling, dropdown results, keyboard nav, and loading/empty/
  error states
• made result rendering customizable while keeping a sensible default layout
• added docs and a live example using OfficeDropdown with hasData
• wired the docs example to the CDA catalog/LOCATIONS endpoint, matching @LaurenAllin current
  search approach

Notes

• Takes an office and provides catalog entries, onSelect to override

[LaurenAllin]

This mostly works as expected - but I still need to test a few additional features. I added a commit with a suggested styling change to avoid the icon and the input text from overlapping.

A couple of suggestions:

1. It would be nice to have an option to add an ignore/blacklist array into the component as a user defined/optional property, with a function in the SearchInput.tsx to filter out any ids that match an item in the array.
2. There is not an endpoint that I can find that would allow this, but a nice to have in the future would be a way to search by public name rather than location id. A user might try to search for Lock and Dam XX, but this will return nothing. The user would have to know to search for LockDam_XX, which is not user friendly.

[LaurenAllin]

Finished testing properties for the SearchInput component. All properties seem to be working as expected except for errorMessage. When the errorMessage is set to a string (i.e. errorMessage="Error"), the search box will only return the error message, even when there is no error.