Currently an application needs to be restarted before it can see
any changes made to the standard shortcut configuration. To notify
about changes a new class is introduced that looks for those
changes using KConfigWatcher and also updates the global map.
CCBUG:426656

In Qt6 the Q_GLOBAL_STATIC will already report to be null while it is in
the process of being deleted, we therefore cannot access it anymore from
destruction code path as we did before.

This problem is hit for example by the Breeze style, making all 6 based
widgets applications crash on exit without this.

So that #include <kconfig_version.h> still works after changing its
location in the previous commit.

NO_CHANGELOG

The eliminated duplication of the composite condition was error-prone
and less readable.

entryMap is ordered by the group name first. So there is no need to
iterate over the entire map to process entries whose group names start
with some prefix. Find the group name prefix's lower bound and iterate
over the proper subrange instead. This should be much faster, especially
if the subrange's size is much less than the entryMap's size.

Adjust isGroupOrSubGroupMatch() helper function to assert the extracted
startsWith() condition instead of rechecking it. Pass
KEntryMapConstIterator in place of the group name to this function in
order to simplify its callers' code. Reuse this helper function in
KConfigPrivate::copyGroup().