Allow disabling either linting or formatting in standard.yml configuration

[schpet]

similar to how rome lets you control wether you are either formatting or linting

• https://docs.rome.tools/configuration/#linterenabled
• https://docs.rome.tools/configuration/#formatterenabled

i'm wondering if it would make sense for standard to also allow opting out of either linting or formatting by configuration.

this came out of #482 but i didn't want to conflate that issue (formatting compatibility) with this feature request. i'm interested in using standard as a linter, without its formatting features.

[searls]

Have to think about this. First impression is that I am… not opposed.