mu4e: add 'c' binding to mu4e-search-query and remove 'cc' binding

[RyanGibb]

mu4e-search-query was introduced in mu4e v1.12.0:

• New command mu4e-search-query (bound to =c=) which lets you pick a query (from bookmark / maildir shortcuts) with completion in main / headers / view buffers.

Bindings are added for the main and headers view.

Upstream binds c to mu4e-search-query, and we follow every other binding on the main screen, so we drop the colliding cc binding

See #844, and #860.

[LoganBarnett]

@RyanGibb doesn't this have the same problem in that we have the other prefixes for things like c e (compose-edit), c r (compose-reply), etc? We'd have to push for those alternative keybindings as well.

IMO it's kind of a step back - I liken compose to magit's commit. I hit c and if I want to do the default thing (just make a new message), I hit c again. But for the compose alternatives I can see those via which-key. That said, my opinion doesn't mean much, and I would indeed mean retaining a deviation from mu4e's default bindings.

I can always override back to the old behavior, and make mu4e-search-query something I can remember (maybe like Q or S). So this isn't terribly a big deal to me :)

[RyanGibb]

Hmm, that's a good point. What if we bound C to mu4e-search-query?