Improvements on AWS SSO utility tool

[lucasjrt]

I've added some features to improve usability of the script, and also fixed some scenarios that the script wouldn't work:

• Add: Improve usage instructions to be more descriptive
• Add: Support multiple roles, as in large organizations accounts are likely having more than a single access role
• Add: Support for AWS CLI session, this way it's possible to authenticate only once for all the profiles in the same session
• Fix: Not all (at least mine didn't have) shells have the variable AWS_DEFAULT_REGION set, so I've added the default value of us-east-1
• Add: Support for execution from within a WSL environment
• Fix: Accounts with spaces in the name weren't supported, I've made some changes in order to accept those as those are valid names