Add support for -t / --team on teams

[raulb]

There are other commands like heroku members that do support -t and --team and even encourages their use.

I think switching between commands that support this flag and others that doesn't, it might be really confusing to the user:

e.g.:

› heroku members -o my-team
[email protected]    member
[email protected]     admin
 ▸    my-team is a Heroku Team
 ▸    Heroku CLI now supports Heroku Teams.
 ▸    Use -t or --team for teams like my-team

› heroku members -t my-team
[email protected]    member
[email protected]     admin

› heroku apps -t my-team
 ▸    Error: Unexpected flag -t
 ▸    Usage: heroku apps
 ▸
 ▸    This flag is invalid for this command. Here are the accepted flags:
 ▸     -A, --all           # include apps in all organizations
 ▸     -o, --org ORG       # organization to use
 ▸     -p, --personal      # list apps in personal account when a default org is set
 ▸     -s, --space SPACE   # filter by space
 ▸     --json              # output in json format
 ▸
 ▸    See more information with heroku apps --help

cc @simpsoka @ike-delorenzo