[UX] Add currently activated account for the sky check and check for disk-tier options

[Michaelvll]

This PR adds an --all option for the sky check, so that the user could see more details about the enabled cloud, such as the currently activated account.

This PR also adds checks for the --disk-tier option

Tested (run the relevant ones):

• Code formatting: bash format.sh
• Any manual or new tests for this PR (please specify below)
  • sky check -a
• All smoke tests: pytest tests/test_smoke.py
• Relevant individual smoke tests: pytest tests/test_smoke.py::test_fill_in_the_name
• Backward compatibility tests: bash tests/backward_comaptibility_tests.sh

[cblmemo]

LGTM! Just a small UX concern: the name of the argument --all sounds a little bit confusing and could be misinterpreted as checking all clouds (which implies that the sky check would only check certain default clouds without this argument). Should we consider using -v / --verbose or exploring other options? 🤔 If there are no better alternatives, the --all option should be fine.

[cblmemo]

BTW, shall we update the docs in docs/source/reference/cli.rst to support this newly added flag?

[Michaelvll]

Thanks for the review @cblmemo! -v sonuds good to me. Just updated the option name.

BTW, shall we update the docs in docs/source/reference/cli.rst to support this newly added flag?

The cli document is automatically generated. The new option should be automatically show up after merging.

Also, I just add a option check for the --disk-tier so that it will only allow the three options when it is passed by the sky launch --disk-tier

[cblmemo]

Just tried it out. LGTM!