chore: add available options for perm on error

[vasco-santos]

This PR adds more information on the auth CLI error. My flow to use the auth command was:

$ lotus auth
NAME:
   lotus auth - Manage RPC permissions

USAGE:
   lotus auth command [command options] [arguments...]

COMMANDS:
   create-token  Create token
   api-info      Get token with API info required to connect to this node
   help, h       Shows a list of commands or help for one command

OPTIONS:
   --help, -h     show help (default: false)
   --version, -v  print the version (default: false)

$ lotus auth api-info
ERROR: --perm flag not set

This PR suggests the enhancement of the error to:

$ lotus auth api-info
ERROR: --perm flag not set, use with one of: read, write, sign, admin

We can also use lotus auth api-info --help, but I think that creates some confusion as commandOptions seem optional. This helps the user to be able to just act instead of trying to figure out what the problem is.

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I would also like to discuss the usage of the read token. It is not mandatory for the client, are there thoughts about having it required? Otherwise, we could remove the read option as it is quite useless at this moment.

We could iterate on:

lotus auth create-token --write
lotus auth create-token --sign
lotus auth create-token --admin
lotus auth api-info

The api-info would return all the available tokens for each type of permissions. Let me know your thoughts and I can update this PR or create a follow up