[replace-across-files] Unify the Search Results Panel FindInFiles/ReplaceAll

@nj I just merged with master, and fixed several issues. I wasn't able to move all of the update code to the global search panel, since we will need to add parts of the searches and I wasn't sure how you wanted to handle that. It should be pretty easy to, and we should do it eventually.

Your branch is a bit behind master, so there are a few extra commits here. I guess that might not be much of a problem since this PR just mainly touches FindInFiles, and FindReplace, plus a few tempaltes and adds a new SearchResults file. But I just wanted to create a new PR.