ci: make fat qt libs thin (#6281)

* ci: strip fat qt binaries

* parallelize

* cache thin qt

* print libs

* change qt install dir in the action

* move qt install logic to separate job

* lookup only

* debug: show contents of QTDIR

* enableCrossOsArchive also when saving

* check one dir up

* change install dir

* keep debugging

* try deleting cache

* force delete cache

* pass gh_token

* pass missing params

* use api

* change cache key, disable cross os archive

* move job directly to steps

* add comments

* set cache param directly

* address comments

* fixup

* Update .ci/thin_macos_qtlib.sh

* resolve qt version

* move resolution to separate script

* use single line for run:

* improve error handling in new scripts

---------

Co-authored-by: ebbit1q <ebbit1q@gmail.com>

.ci/compile.sh

@@ -156,6 +156,18 @@ function ccachestatsverbose() {
 
 # Compile
 if [[ $RUNNER_OS == macOS ]]; then
+  # QTDIR is needed for macOS since we actually only use the cached thin Qt binaries instead of the install-qt-action,
+  # which sets a few environment variables
+  if QTDIR=$(find "$GITHUB_WORKSPACE/Qt" -depth -maxdepth 2 -name macos -type d -print -quit); then
+    echo "found QTDIR at $QTDIR"
+  else
+    echo "could not find QTDIR!"
+    exit 2
+  fi
+  # the qtdir is located at Qt/[qtversion]/macos
+  # we use find to get the first subfolder with the name "macos"
+  # this works independent of the qt version as there should be only one version installed on the runner at a time
+  export QTDIR
 
   if [[ $TARGET_MACOS_VERSION ]]; then
     # CMAKE_OSX_DEPLOYMENT_TARGET is a vanilla cmake flag needed to compile to target macOS version