We:
1. Set up a nice TMPDIR for our tests to use
2. Immediately `cd` to the directory containing the test runner.
So instead we don't do (2), and stay in the temp directory, and
explicitly use all the things from the test runner directory.
I am fairly certain that cmake papered over this by adding a second
layer of temp dir.
See the changelog additions for user-visible changes.
Since we enable/disable terminal protocols whenever we pass terminal ownership,
tests can no longer run in parallel on the same terminal.
For the same reason, readline shortcuts in the gdb REPL will not work anymore.
As a remedy, use gdbserver, or lobby for CSI u support in libreadline.
Add sleep to some tests, otherwise they fall (both in CI and locally).
There are two weird failures on FreeBSD remaining, disable them for now
https://github.com/fish-shell/fish-shell/pull/10359/checks?check_run_id=23330096362
Design and implementation borrows heavily from Kakoune.
In future, we should try to implement more of the kitty progressive
enhancements.
Closes#10359
