Fixed issues introduced by upgrading to Qt 5.15.
WIP: upgrade to Qt 6
WIP: QML fixes. [sklp-ci]
WIP: macOS font fix.
WIP: backend is a now a singleton.
WIP: remove version number of import.
WIP: fixed missing Action in qmldir.
WIP: fixed errors on program exit.
WIP: CMake detects host arch on mac if not specified.
Other: renaming of bridge-gui.
WIP: locate bridge exe.
WIP: bridge process launch.
WIP: cleaner closure of bridge.
WIP: grpcClient connection retries.
WIP: clean exit when bridge process is killed.
Fixed issues from MR review. [skip-ci].
WIP: Fixed gRPC case in CMakelists.txt [skip-ci]
It caused issues on Debian.
WIP: update gRPC/protobuf and tweaked CMakeLists.txt. [skip-ci]
WIP: Fixed a bug where splash screen could not be dismissed. [skip-ci]
