feat: added create, move, capabilities, count, list, fetch

[bkono]

Large run of changes here. Doc comments are present for each of the following new actions covering them in detail:

• list: returns the names of mailboxes that match the given pattern
• capabilities: A list of capabilities supported by the server
• has_capability?: Check of specific server support for a capability
• move: Move messages from current mailbox to a destination mailbox
• create: Create a new mailbox (aka folder)
• fetch: Fetches prior messages based on a sequence set. Messages are delivered to all subscribers just like new messages.

Also includes a few bug fixes and adjustments necessary to support the additional commands.

I realize it's a fairly large PR, so this isn't a scope of features you want to merge, no worries. Or if you'd like some API related changes, let me know.

[Flying-Toast]

Thanks for getting this through! I have quite a few things on my plate right now while I finish up uni, so I might not get around to reviewing this for a bit but I will do so as soon as I get the chance.

Thanks!

[bkono]

Thanks for getting this through! I have quite a few things on my plate right now while I finish up uni, so I might not get around to reviewing this for a bit but I will do so as soon as I get the chance.

Thanks!

No worries, take your time. I also have some small bug fixes (datetime parsing has an edge case) and connectivity related changes I can PR later if you'd like.