Support multi-line search for Global search

[sandy081]

Support multi-line search for Global search

• Background search implementation for multi-line search
• Adopt results for multi-line. Eg: Matches
• Adopt Replace functionality for multi-line. Eg: Matches

[ocaraveo]

This feature/bug-fix should be prioritized better.

I use global search to find type definitions and make code refactoring decisions based on results, e.g. "find all uses of ..." some particular piece of code.

I've seen, tested, and verified specific scenarios where searching for a search-term using Global Search (with Match Whole Word -on) doesn't turn up a matching result, even though there's a file with that search-term in it. If I open the known file, Global Search will only then start showing the matching result. -- #13068, #9051, #18671

In short, Global Search is a critical feature for helping refactor code, without this improvement I can't trust VS Code search functionality to help me produce quality code. Thanks for the effort. Please get this in.

[rshpeley]

Komodo edit gets this right, but I'd like to switch to vsc. I use multiple line search/replace in files all the time and vsc should support it.