RLS should have finer grained build options in addition to all_targets

[aloucks]

It would be nice if we could have finer grained build options instead of only all_targets. There are often times when I'd like to build all binaries or examples, but not the tests. It looks like cargo has support for this:

$ cargo check --help | rg "Check all"
        --all                       Check all packages in the workspace
        --bins                      Check all binaries
        --examples                  Check all examples
        --tests                     Check all tests
        --benches                   Check all benches
        --all-targets               Check all targets

We should add these options:

• all_packages
• all_binaries
• all_examples

[alexheretic]

I've found it not a big deal for examples, as when you're editing an example changes only require the example itself to be recompiled which is generally fast.

However, switching off all_targets can help when editing the main code on crates with lots of examples, tests, etc as each target will be recompiled after each change by default. Worse users need to wait until all targets have finished churning before getting to see an early error #1059.