Need to set up CI to test frontend & backend

[leofang]

This is the sibling issue of NSLS-II/ptycho#39.

[leofang]

Now we have CIs running on a local GPU machine (#90, #91), but currently we only test if the package can be built.

Next steps:

• Set up another Azure/GH CI that uses the default runners (not our own machine) --- This can be used to test CPU codes
• Write tests to actually run CPU/GPU codes
• Move the local CIs to containers (currently the runners are under a local user space)

[leofang]

I think our local CI can be used to build a conda package locally for releases. Probably needs a webhook for kicking it off on GitHub.

[leofang]

Another thing: investigate if the GPU CI can be invoked only when needed.