all: remove type: support

[keegancsmith]

This was added a few years ago and was never used. Originally I added it
for supporting hierarchical queries in Sourcegraph. But we never shipped
the stuff I worked on on the Sourcegraph side, but the code remained in
Zoekt. This deletes likely one of the most significant divergences from
upstream.

We may want something like this again in the future. But according to
Rijnard it is hard to directly use this feature since it doesn't work
the same way and/or queries work in Sourcegraph. So best to remove.

[rvantonder]

cool cool. it's actually not as big a diff as i thought, so yeah, makes it easier if we felt like revisiting later later

[keegancsmith]

FYI we do use type support in Sourcegraph! So I have reverted this: https://github.com/sourcegraph/sourcegraph/blob/1f83100fc625fc361d9cd640dc0dd64684c4da3b/cmd/searcher/search/zoekt_search.go#L73-L86

[rvantonder]

Oh, you know what this is Keegan, it's (strictly) logic for repoHasFile:

https://sourcegraph.com/github.com/sourcegraph/sourcegraph@1f83100fc625fc361d9cd640dc0dd64684c4da3b/-/blob/internal/search/run/repository.go?L96:84&subtree=true

It makes sense that this still exists (sorry missed that originally). We don't need type:repo for anything else. We've deprecated repoHasFile in favor of repo:contains, but have not removed repoHasFile yet. We haven't removed repoHasFile yet for <reasons>. Let's keep this around, I'll let you know when there's an update and how to go about this next.