Add new "Debug intrinsics" filter. (#5045)

For now, this removes all `llvm.dbg.*` calls from LLVM IR. This is
useful to keep coloring the line correspondence between source and IR,
while not polluting the IR with the debug intrinsics.

Admittedly, I don't have much of a clue of what's going on here, so I
might be missing obvious adaptions (e.g. can we disable this for all
non-LLVM compilers for now somehow?).
Also, not really a Node.JS testing wizard either... 🤷🏼 

Just wanted this really bad for a workshop that's coming up soon ^^

Only tested with my system's default `clang` for now.

Fixes #5044

---------

Co-authored-by: Matt Godbolt <matt@godbolt.org>

docs/API.md

@@ -73,7 +73,8 @@ To specify a compilation request as a JSON document, post it as the appropriate
              "intel": true,
              "labels": true,
              "libraryCode": false,
-             "trim": false
+             "trim": false,
+             "debugCalls": false
         },
         "tools": [
              {"id":"clangtidytrunk", "args":"-checks=*"}