ChangeCompileCommandsNotification is sent/processed even if a configuration provider is used instead of compile commands

[sean-mcmanus]

It seems like it should only be sent/processed if compile commands is actually being used for configuration.

[sean-mcmanus]

If compileCommands is set, then it could still be used as a fallback if the configuration provider doesn't have a configuration for a file, but if compileCommands is not set then there's no need to send an update for one.

[Colengms]

I don't think these notifications cause a perf issue. They simply result in a dirty flag being set on the native side, causing the compile_commands.json to be re-parsed the next time its contents are required.

It would be nice to avoid sending redundant notifications, but I think that might need to be part of a more wholistic change, to ensure changes are properly synchronized with TU creation.

We have some work (currently on the back burner) to address #6931 , which may result in the current compile_commands.json handling being replaced (processed entirely on the TypeSide side).