[Feature Request] Allow setting `--info=<error-code>` from the command line

[rchen152]

All of the following work:

• pyrefly check --error=deprecated
• pyrefly check --warn=deprecated
• pyrefly check --ignore=deprecated

But this doesn't work:

• pyrefly check --info=deprecated

even though "info" is a valid severity level that I can set in pyrefly.toml.

[AryanBagade]

hey @rchen152 , @yangdanny97 can i work on this!!!