refactor: session connection logic

[markfeinstein]

Refactoring of the code handling connections to tmux sessions.

• Update the way sessions are identified to check the session name and path, correcting a bug where switching to a session with a name that does not match the path resulting in a new session being created.
• Eplicitly handle creating a new session when connecting to a valid filesystem path that does not correlate to an active session.
• Establishes a new pattern for the tmux package using a struct with methods to interact with the CLI. This will be the basis for supporting dependancy injection to improve testability of the code base.

[markfeinstein]

@joshmedeski I've addressed or responded to all the open issues, please take another look when you have a chance.

There is no corresponding issue for the problem being fixed here, just something I came across locally.