log: Make --all configurable

[abhinav]

It didn't sit right to land the configuration system change without actual configuration options.

Add the ability to make the -a flag in gs ll and gs ls default to true by setting spice.log.all, and make documentation updates to ensure that all configuration options are documented.

[abhinav]

This change is part of the following stack:

• 328 ◀

  • 327

_{Change managed by git-spice.}

[abhinav]

Documentation changes: