Provide support for bot resources API

[weibeu]

This will add API for resources which aren't provided under OAuth2 and require bot token as an authorization to make request. This means that it is similar to as what discord.py provides you.

[dosubot]

Hi, @weibeu. I'm Dosu, and I'm helping the Flask-Discord team manage their backlog. I'm marking this issue as stale.

Issue Summary:

• You requested an API feature for accessing resources requiring a bot token, similar to discord.py.
• This feature aims to access resources not available through OAuth2.
• No further comments or developments have been made on this issue.

Next Steps:

• Please let us know if this issue is still relevant to the latest version of the Flask-Discord repository by commenting here.
• If there is no response, the issue will be automatically closed in 7 days.

Thank you for your understanding and contribution!