This switches Alacritty's default configuration format from yaml to
toml. While yaml is still supported, it is done by converting it to toml
and should be removed entirely in the future.

All existing features were persisted based on my testing. Behavior
should not change much, though `--option` might have slightly different
behavior since the entire line is not interpreted as one line of toml.

A new `alacritty migrate` subcommand has been added which allows
automatic migration from yaml to toml. This also could be used as a
facility to automatically fix configuration file changes in the future.

Closes #6592.

Signed-off-by: Dennis Maier <d.maier94@web.de>
Co-authored-by: Christian Duerr <contact@christianduerr.com>

This adds a codesign step to our makefile build which should
automatically sign the application and resolve the issues on M1 macs
where Alacritty constantly requests permissions.

Since self-signing does still seem to fix this issue after sharing the
resulting `Alacritty.app` with other M1 macs, the binary produced by our
release build should also be fixed automatically.

Fixes #5840.

The original multiwindow PR added a new manpage, however this was not
properly documented or included in our CI. This patch resolves these
issues.

This commit also purges .gitignore, since the files mentioned in it
should be handled by global ignore file.

Fixes #4378.

Fixes #2653.