Multiple flychecks with different commands for single workspace

[mladedav]

I'd like to have rust analyzer run one flycheck with clippy and another with cargo doc so that I can also fix documentation issues.

The only workaround I have found until now is to change the command and restart RA or possibly have an utility that runs both so that RA sees it as a single cargo command.

This would probably mean that the rust-analyzer.check.* settings would have to be merged into one object and there would have to be an array of these.

For example cargo doc does not support --all-targets but I'd like to keep that setting for clippy.

An alternative would be to add a second flycheck specifically for running cargo docs with its own rust-analyzer.docs-check.* configurations. It might be enough (probably would be for me), but maybe there would be other use cases for running multiple different flychecks.