[productivity] (vscode) add server test launch configurations

[pq]

Spending a bit of time on devtools yesterday, I found myself really appreciating the pre-populated run configurations. It would be great (especially for casual contributors) to do the same for server/analyzer/linter.

---

Launches

• server test: all
• linter test: all

Tasks

• server generate files

[FMorschel]

I was debugging just now with the latest commit and my vscode launch got automatically changed to one of the inner launch-configs (I think this is the default behaviour since that one is more specific). I got a bit confused because I had just a few tests (running pkg\analysis_server\test\src\services\correction\assist\flutter_wrap_builder_test.dart) and now it was running many tests I didn't even know about.

I was talking to @DanTup, and he suggested these launch files could have a "single file" launch too and have that first. WDYT?

Something like:

{
  "name": "Current file",
  "request": "launch",
  "type": "dart",
  "program": "${file}",
}