[vscode] support when closure for views

[akosyakov]

What it does

fix #5853 - support when closure for views:

• a view visibility should be auto toggled based on when view closure
• if a user explicitly hides a view, then auto toggling should be disabled
• and it should be enabled again when a user explicitly unhides the view

How to test

• install vscode sample tree extension: https://github.com/microsoft/vscode-extension-samples/tree/master/tree-view-sample
• use json outline example, it should be toggled only when json file is opened

See for how install VS Code extension :https://github.com/theia-ide/theia/wiki/Testing-VS-Code-Extensions

Review checklist

• as an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• as a reviewer, I agree to behave in accordance with the review guidelines

[akosyakov]

@kpge Could you test please whether it fixes #5853 with npm extension? Thank you!

[kpge]

@kpge Could you test please whether it fixes #5853 with npm extension? Thank you!

@akosyakov LGTM

• The npm scripts is disappeared by default(config.npm.enableScriptExplorer = false)
• The npm scripts is displayed when config.npm.enableScriptExplorer = true

but I think npm config should be always displayed in Preferences dialog , no matter the project is a npm project.
in a java project:

in a npm project:

[akosyakov]

but I think npm config should be always displayed in Preferences dialog , no matter the project is a npm project.

@kpge Thank you for testing the PR! Could you file a separate issue for it? We need to check how it behaves in VS Code before fixing as well. If you can do it, it would help.

[AlexTugarev]

Nice @akosyakov! I quickly checked that it properly registers the JSON type of the current editor in the example plugin. Code looks good to me as well!