🐛Fix kernel not dispose when closed

[AdrySky]

Description

This will fix the 'zombie' kernel still exist when closing/refreshing tab.

Also, as discussed before, remove the need to create a kernel every time run button clicked. Currently, it'll use the same kernel as long as the output panel still exist.

References

#55

Pull Request Type

• Xircuits Core (Jupyterlab Related changes)
• Xircuits Canvas (Custom RD Related changes)
• Xircuits Component Library
• Documentation
• Others (Please Specify)

Type of Change

• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Tests

1. Try running xircuits multiple times without closing the output panel.
   1. The xircuits shouldn't prompt user to select a kernel after the first run.
   2. It'll only use the kernel created when the first run was clicked.
2. Try running xircuits and then remove the output panel.
   1. Try run it again and it should prompt user to select a kernel.
3. While the output panel exist, close/reload the tab.
   1. The xircuits's kernel shouldn't exist in the 'Running Kernels' panel.

Tested on?

• Windows
• Linux Ubuntu
• Centos
• Mac
• Others (State here -> xxx )

Notes

Don't manual close the xircuits's kernel in the 'Running Kernels' panel. It'll break the xircuits kernel and refresh is needed to fix it.

[MFA-X-AI]

What a fast pull request, thanks!
Can confirm that the tests work in this pull request. I believe this will help users to not have zombie kernels for long running sessions. Great work!