servoshell: Replace getopts with bpaf for argument parsing (#37194)

This includes some small refactoring and some small breaking changes as
listed below. Other than these I tried to keep the functionality exactly
the same but because in the old code the parsing and settings of
preferences was intermingled it was difficult to figure out.

Small Breaking:
- Size and resources-path were unused but appeared in the help.
- soft-fail and hard-fail: Soft-fail flag got removed because it is too
  difficult to keep both. The default is now soft-fail and hard-fail can
be enabled.
- The help strings are obviously formatted differently now.
- -V does not work anymore but -v and --version.

Ideally, we want to have the ServoShellPreferences and Preferences be
directly the Argument structure but that needs a bit more discussion
because it would break backwards compatibility with the commandline.

This increases the binary size by ~280kb.

Testing: The testcases are still working but they do not cover much.
I added a unit test for the -p flag because it is the most difficult to
parse in general.
Fixes: This will fix a small number of various parsing misshaps. It will
also show if we are removing an option via unused lint.

Signed-off-by: Narfinger <Narfinger@users.noreply.github.com>

Cargo.toml

@@ -64,7 +64,6 @@ fnv = "1.0"
 fonts_traits = { path = "components/shared/fonts" }
 freetype-sys = "0.20"
 fxhash = "0.2"
-getopts = "0.2.24"
 gleam = "0.15"
 glow = "0.16"
 gstreamer = { version = "0.23", features = ["v1_18"] }