shortcuts: Ignore consumed modifiers for mnemonics

This is necessary to make mnemonics like Alt-1 work in
layouts where numeric keys are shifted, like AZERTY.

Fixes: #3912
12 jobs for shifted-mnemonics in 17 minutes and 30 seconds (queued for 1 second)
Status Job ID Name Coverage
  .Pre
passed #1279872
style-check-diff

00:03:34

 
  Build
passed #1279873
fedora-x86_64

00:05:59

passed #1279875
installed-tests

00:15:44

passed #1279877
macos
macos

00:13:07

failed #1279876
win32-ps
msys2-mingw64

00:01:12

passed #1279874
release-build

00:06:55

 
  Analysis
failed #1279879
asan allowed to fail
asan-build

00:15:19

passed #1279878
static-scan

00:09:55

 
  Docs
passed #1279880
reference

00:17:29

 
  Flatpak
manual #1279881
flatpak allowed to fail manual
flatpak-manual:demo
manual #1279883
flatpak allowed to fail manual
flatpak-manual:icon-browser
manual #1279882
flatpak allowed to fail manual
flatpak-manual:widget-factory
 
Name Stage Failure
failed
msys2-mingw64 Build
Reason: The process cannot terminate itself.
kill: 1712: No such process
kill: 1713: No such process
Fetching changes...
Reinitialized existing Git repository in C:/_r/_builds/k3_3muaB/0/GNOME/gtk/.git/
Checking out 0768cfb7 as shifted-mnemonics...
warning: failed to remove _build/: Permission denied
Cleaning up file based variables
ERROR: Job failed: exit status 1
failed
asan-build Analysis
 - css: 214 total, 213 pass, 1 fail
Processing gtk suite a11y:
- a11y: 22 total, 20 pass, 2 fail
Processing gtk suite tools:
- tools: 4 total, 3 pass, 1 fail
Processing gtk suite reftest:
- reftest: 132 total, 130 pass, 2 fail
Cleaning up file based variables
ERROR: Job failed: exit code 1