Add ProgressBar and LoadingBar widgets to SPA and create gallery samples

for them.

The loading bar is indeterminate, and expresses the loading status or
waiting time. The progress bar is reflecting the progress of a process,
and need a progress fraction input.

Test: Unit test and manually test on device
Bug: 254364764
Change-Id: I7faf20beab1e46c5c9d4a9ab07a916a7f506412c