new welcome page every time when I refresh my workspace

[vitaliy-guliy]

Describe the bug

Che-Theia always open a new Welcome page when refreshing the workspace.
It looks like the bug is appeared after merging this PR eclipse-che/che-theia#605
I have a strong opinion that we have to revert that branch.
We don't need to store the Welcome page, let the welcome plugin decide whether it should be opened or not (depends on config in preferences).
BTW, on restored welcome page, hyperlinks with commands does not work.

Screencast with the bug https://youtu.be/Ija0oU-i2AY

Che version

• latest
• nightly

Steps to reproduce

1. Create and open a workspace.
2. Refresh the browser.
3. Refresh the browser.
4. ...

Expected behavior

One welcome page with working hyperlinks.

Runtime

• minikube (include output of minikube version and kubectl version)

Screenshots

Environment

• my computer
  • Linux

[vitaliy-guliy]

To solve this issue need to be merged

• Do not serialize webview if the serializer for the webview is not set eclipse-theia/theia#8473 - is not relevant anymore. Theia master branch does not have any issues with webviews. Webviews in Che-Theia will work properly after aligning with upstream Theia and merging this PR Update to the latest Theia che-theia#823
• Do not store state of Welcome page che-theia#848

[azatsarynnyy]

FYI: Che Theia is already aligned with upstream Theia eclipse-che/che-theia#823
So, you can check if the issue is solved.