Incorporate stac-check

[gadomski]

Is your feature request related to a problem? Please describe.
We've had halting support for using upstream validators as a part of the stactools cli, e.g. #191 and #151. There's probably space for taking a step back and making the stac validate story a bit more coherent, but as an incremental improvement we could include the new https://github.com/jonhealy1/stac-check project.

Describe the solution you'd like
Add a stac lint command, e.g.:

stac lint simple-item.json

This could include a --recursive option to lint an entire tree.

Describe alternatives you've considered
There could(/should) be a higher-level stac validate command that includes linting. There's also some common "take this STAC catalog and report on it" architecture common between stac info, stac validate, and ??? that could be refactored.

Additional context
None

[jonhealy1]

Hi. I have made a draft pr. I have added a lint option to the cli. I have also added the basic STAC best practices warning messages from https://github.com/jonhealy1/stac-check. I could add some of the validation messaging I use too if wanted, which mostly comes from the stac-validator project: https://github.com/sparkgeo/stac-validator

[gadomski]

This is great! I dropped an initial review on #254 with a couple of notes.

Since stac-check will bring in stac-validator as a dependency, I think it will make sense to switch the stactools validation command to use stac-validator. That doesn't have to happen in #254, I'm happy to do it myself in a follow-on PR.

Thanks again for the contribution, stac-check looks like a great tool!