Make disabling formatting explicit

[enwi]

With the current version it is not possible to explicitly disable external & auto found formatters while still being able to use the internal mago fallback. This PR adds an explicit flag to disable formatting entirely, removing the previous check when all tools are disabled.

Checklist

If applicable:

• I have updated CHANGELOG.md
• I have updated the documentation (README.md, docs/, examples/)
• I have updated the config schema (config-schema.json)
• I have added/updated tests to cover my changes
• I fully understand the code that I am submitting (what it does,
  how it works, how it's organized), including any code drafted by an LLM.

[enwi]

@AJenbo If for whatever reason you think this should be implemented differently, just go for it. This is just a temporary fix for our project.

[calebdw]

• disabled results in a double negative which is confusing---would rather the option be named enabled which is true by default
• the config schema needs to be updated