More flexible "move" command in thread mode

[pacien]

Is your feature request related to a problem? Please describe.

Currently, the "move" command in thread mode only accepts notmuch queries with the "next" and "previous" subcommand.

It doesn't support:

• combining multiple subcommands to allow something like: "move first unfolded"
• the use notmuch queries with other subcommands, like: "move first tag:unread"

This is quite inconvenient and prevents the user from defining shortcuts such as "select; move first tag:unread" in the search mode to open a thread and focus directly on the first unread message [1].

Describe the solution you'd like

The "move" command could be made more flexible to allow the combination of multiple filters (currently subcommands) and the use of notmuch queries.

Describe alternatives you've considered

In the scenario [1]: using "select; move next tag:unread" moves to the second unread message in new threads, which is not the desired effect.

Additional context

Turning subcommands into filters could actually simplify the implementation of that command.

[pazz]

Yes, that'd be cool. Also, It be gread to write this somehow so that it doesn't blow up the code to 10000 lines. Suggestions welcome :)