Implement search for group wikis

What does this MR do and why?

This MR extends the search feature to the group wikis. Add a new attribute group_level_blob in the Gitlab::Search::FoundBlob which differentiates the project blob from the group blob. Replace the project implementation in the GitClassProxy with the container. Created a new FoundWikiPage inside the ee to support the group wikis which instantiates the wiki for the group search results. And at last add the group_ids as well in the routing to search for group wikis.

Screenshots or screen recordings

An extra search result in the After is the group wiki

Before	After

How to set up and validate locally

1. Ensure the elastic search is enabled
2. Create some project wikis, group wikis, subgroup wikis, project wikis in the group, and project wikis in the subgroup with the name qwerty
3. And do the global search with the term qwerty. You should see everything in the search result.
4. Perform the group-level search. You should see the wikis inside that group and project wikis under that group and the group wikis in the subgroup of that group.
5. Perform a project search. And you should see only wikis from that project

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #336100 (closed)