Fire onDidChangeViewState for interactive window

[joyceerhl]

Fix #7249

The interactive window used to be a webview panel so it had its own view state change event. Needed to hook that event up to window.onDidChangeActiveNotebookEditor as we're now working with an editor instead. Comparing NotebookEditors here instead of comparing stringified URIs should be safe because they're fat objects so shouldn't be recreated in the extension host.

[codecov-commenter]

Codecov Report

Merging #7596 (5162d8d) into main (adc3601) will increase coverage by 0%.
The diff coverage is 100%.

@@          Coverage Diff          @@
##            main   #7596   +/-   ##
=====================================
  Coverage     66%     66%           
=====================================
  Files        365     365           
  Lines      22650   22652    +2     
  Branches    3440    3441    +1     
=====================================
+ Hits       15099   15104    +5     
+ Misses      6263    6258    -5     
- Partials    1288    1290    +2     

Impacted Files	Coverage Δ
...atascience/interactive-window/interactiveWindow.ts	54% <100%> (+<1%)	⬆️
...ence/editor-integration/cellHashProviderFactory.ts	97% <0%> (-3%)	⬇️
...client/datascience/kernel-launcher/kernelDaemon.ts	56% <0%> (-2%)	⬇️
src/client/datascience/baseJupyterSession.ts	68% <0%> (-1%)	⬇️
...ce/interactive-window/interactiveWindowProvider.ts	72% <0%> (+1%)	⬆️
...tascience/jupyter/kernels/kernelCommandListener.ts	58% <0%> (+2%)	⬆️