bug#60880: 30.0.50; tree-sitter `treesit-explore-mode' is buggy and does not behave properly

[Mickey Petersen]

A medley of issues here:

1. Executing `treesit-explore-mode' on a buffer with no valid grammar
support causes the minor mode (and playground buffer) to stick around and 
"load" anyway.

2. Bailing out of the grammar prompt does not, in actual fact, stop explore 
mode from proceeding. Instead it creates an empty buffer and it still engages 
the minor mode.

3. Killing the playground buffer does not remove the explore mode buffer.

4. treesit-explore-mode is stored against a buffer during `desktop-save' (and 
subsequently read with) `desktop-read'. Thus broken buffers or files inherit 
the explore mode. This is especially pernicious due to #1, #2, and #3.




In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.20, cairo version 1.16.0) of 2023-01-17 built on mickey-work
Repository revision: bb383a54910c3094e5d228e0af62bf70e36203ca
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12013000
System Description: Ubuntu 20.04.3 LTS

Configured using:
 'configure --with-native-compilation --with-json --with-mailutils
 --without-compress-install --with-imagemagick CC=gcc-10'