Add defcustom for major-mode remapping

[yuhan0]

Closes #63

Naming of defcustom / commands open to change, if alright I can go ahead and edit the changelog/Readme

---

Before submitting a PR mark the checkboxes for the items you've done (if you
think a checkbox does not apply, then leave it unchecked):

• The commits are consistent with our contribution guidelines.

• You've run M-x checkdoc and fixed any warnings in the code you've written.
• You've updated the changelog (if adding/changing user-visible functionality).
• You've updated the readme (if adding/changing user-visible functionality).

Thanks!

[bbatsov]

Looks good.

I noticed clojure-ts-mode also adds separate modes and mappings for jank and ClojureDart, and I think clojure-mode that just maps them to clojure-mode, but we can address this discrepancy.

[bbatsov]

Perhaps clojure-ts-auto-remap or clojure-ts-auto-remap-modes would be slightly better name.

[yuhan0]

I've renamed it to clojure-ts-auto-remap, wasn't sure if it should have a -p suffix being a boolean? Feel free to change it further (maybe the commands too, clojure-ts-activate -> clojure-ts-activate-remapping)

[yuhan0]

I've removed the commit which uses defcustom setter to trigger activate/deactivate calls on setopt, after a few attempts at fixing it was still causing recursive load errors when being called on initial package load.

[bbatsov]

Okay, I guess that will do for now. I thought a bit too late that probably those commands shouldn't do anything if clojure-mode is not around, but I doubt anyone would call them if they don't use clojure-mode to some extent.

[rrudakov]

FYI: https://lists.gnu.org/archive/html/emacs-devel/2025-03/msg00502.html

[bbatsov]

Good to know, I'll update the code to use it.