[FR] Make `repositories` tab much more useful

[komapa]

Hello, sorry that I will make FR related to how neogrok works but we find that their repositories view is much more useful and actually shows detailed information about the repositories like size and files indexed.

The more important feature is the repositories CONTENT search. So searching for TODO case:yes should show all repositories which match the search term. Maybe you can still leave the search for repository names but should be secondary.

[brendan-kellam]

Thanks for the FR. The low hanging fruit here is adding additional information to the table about the repository. I'm guessing the neogrok client is sourcing this information from the zoekt /list API. For each repo, it returns these stats:

This API also accepts a search term, so likely how neogrok is powering repository search. I can definitely see why this is useful in scenarios where you want a list of repositories where a search term exists (e.g., "what repos are using package X @ version Y").

I'm a little hesitant to use zoekt for the search box here since a) it will mean repositories that are still building their initial index will not be searchable, and b) I'd like to keep "code search" type interactions (i.e., using the zoekt search query language) isolated to the /search path. In all likelihood, repository search will be driven by #536 when we add that capability.

I was poking around SG a bit and saw they have the notion of repository predicates that allow you to filter a search on repositories that have content matching the expression. Example. I think adding something like this would be preferable since we would be able to support this class of searches while keeping the code search experience unified to that same search box.