[unstable option] `skip_macro_invocations`

[tommilligan]

trafficstars

Tracking issue for unstable option: skip_macro_invocations.

• [ ] Option documentation.

From discussion here: https://github.com/rust-lang/rustfmt/issues/5324#issuecomment-1111797851

See Processes.md, "Stabilising an Option":

• [x] Is the default value correct?
• [x] The design and implementation of the option are sound and clean.
• [ ] The option is well tested, both in unit tests and, optimally, in real usage.
• [ ] There is no open bug about the option that prevents its use.