Handle multiple compile commands on client side (needs native server side support)

[yiftahw]

closes #7029

DONE:

• [x] updates to the c_cpp_properties.json schema and compileCommands setting to accept either a string or array of strings.
• [x] updates to the settings.json schema and default.compileCommands setting to accept either a string or array of strings.
• [x] a single path with non-zero length in c_cpp_properties.json or settings.json is placed inside an array of length 1.
• [x] empty strings are filtered from the array of paths, a single empty string or an empty array are handled as undefined.
• [x] file watcher support for the list of files provided by the user.
• [x] single compile_commands.json is converted to a list of size 1 to consistently send an array (or undefined).
• [x] handle squiggles for errors in c_cpp_properties.json.
• [x] updated C/C++: Edit Configurations (UI) panel to handle multiple compile_commands.json paths.

  TODO:

• [ ] closed source server side support by the team?

[yiftahw]

@bobbrow squiggles are now handled as well. I believe most of the work on the client side is done.
let me know if you have more feedback.

please note there is a new telemetry entry and a new localized string:

message = localize("multiple.paths.should.be.separate.entries", "Multiple paths should be separate entries in an array.");
newSquiggleMetrics.MultiplePathsShouldBeSeparated++;

[bobbrow]

@bobbrow squiggles are now handled as well. I believe most of the work on the client side is done. let me know if you have more feedback.

Thank you very much. Would you also be able to do the changes to the Edit Configurations UI in Extension/ui/settings.* so that multiple paths can be displayed/edited in that view?

[yiftahw]

looking into it... putting the PR back to draft for now

[yiftahw]

@bobbrow updated the UI panel.
note: adding a single path in the UI will save it as an array of size 1 (similar to how includePath is handled)