Snap deployment issues

[mbektas]

Creating this issue to keep track of Linux Snap issues. Snap deployment is available here but additional work is needed to be able to announce as GA.

1. jlab CLI is not available with snap. It might be possible to support using electron-builder snap hooks.

2. When the app is updated, installer seems to copy the bundled environment installation but not the additional envs installed. This process needs to be better understood.

   a. Making a copy of the bundled env installation is not enough. conda environment is not relocatable by copy paste.
   b. It is not clear if the additional envs installed with previous version will be kept indefinitely.

below is the list of environments after updating from build 5 to 8. jlab_server at the bottom of the list got auto created after upgrade. even though it appears to work, it is not reliable as conda env is not relocatable.

cc. @dmitry-lyfar

[mbektas]

adding CLI support with this PR #800

[mbektas]

fixing Python environment install locations with this PR #801

[mbektas]

both issues are fixed now and Snap is publicly available.