* Add GitHub Discussions custom search service
This commit adds a GitHub Discussions custom search service in the github-discussions-custom-search.service.js file. It includes classes for global discussions search (GithubDiscussionsSearch) and repository-specific discussions search (GithubRepoDiscussionsSearch). Users can now search discussions with custom queries and retrieve the discussion count.
Fixes#9213
* Add tester to GithubDiscussionsSearch
* Add documentation for GithubDiscussionsSearch
Inform users of filters and query values for the free search.
* Update GithubDiscussionsSearch examples
Change examples from filter by author to `filter` by `answered-by` as this has higher change of being a more common use case.
* fix typo
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Co-authored-by: jNullj <jNullj@users.noreply.github.com>
Co-authored-by: chris48s <chris48s@users.noreply.github.com>
