Add missing type hinting to Search module docblocks

This is a sub-issue of #1800046: [META] Add missing type hinting to core docblocks, fix Drupal.Commenting.FunctionComment.Missing* focused on correctly adding @param and @return type hinting to the Search module.

Documentation patches that include type hinting are time consuming to both review and commit because one must dig into the actual code to confirm that the type hints are both correct and complete. Hence, please be patient and try to limit type hint patches to covering only a limited number of docblocks (10-15 as a guess).

How To Review This Issue

1. Attempt to apply the patch to see if it needs a reroll.
2. Use the phpcs one-liner to evaluate whether all the relevant standards errors have been resolved: https://gist.github.com/paul-m/227822ac7723b0e90647
3. Look at each change and determine whether the type hint is correct.

Related sprint issues: