This commit adds a new preprocessor to use `${@searchKeywords}`, allowing
the docs to use a list of custom search phrases that will be
prioritized over the keywords found in the content.
Closes#35449
PR Close#35539
Previously searching for `compose` did not include `Validators`
in the search results because we were not including all the
`static` members of API docs in the index.
PR Close#21988
This is to tidy up the `author-packagse`, which currently duplicates a
lot of the configuration in the main packages. We need to
DRY this up so that we don't fall foul of a change in one being missed in
the other.
