js/shortcut.js: do not launch preset/locus shortucs when .altKey is there

This should enable the new shortcuts on keyboards where some symbol is behind the numeric keys
and accessed with 'Alt' or 'AltGr'.

See #2456.
5 jobs for feature-c/new_shortcuts in 2 minutes and 28 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Test Quality
passed #6640
code_quality

00:00:05

 
  Test Unit
passed #6641
test_browser_unit

00:00:02

 
  Test Functional
passed #6642
test_browser-functional

00:02:15

 
  Deploy
passed #6643
deploy

00:00:05

manual #6644
allowed to fail manual
stop_deploy