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
This matches what we do in --profile's output:
```
> source /home/alfa/.config/fish/config.fish
--> set -gx XDG_CACHE_HOME /home/alfa/.cache
--> set -gx XDG_CONFIG_HOME /home/alfa/.config
--> set -gx XDG_DATA_HOME /home/alfa/.local/share
```
instead of
```
+ source /home/alfa/.config/fish/config.fish
+++ set -gx XDG_CACHE_HOME /home/alfa/.cache
+++ set -gx XDG_CONFIG_HOME /home/alfa/.config
+++ set -gx XDG_DATA_HOME /home/alfa/.local/share
```
This adds support for `fish_trace`, a new variable intended to serve the
same purpose as `set -x` as in bash. Setting this variable to anything
non-empty causes execution to be traced. In the future we may give more
specific meaning to the value of the variable.
The user's prompt is not traced unless you run it explicitly. Events are
also not traced because it is noisy; however autoloading is.
Fixes#3427
