Install vsix files from the explorer view (#13269)

[dhuebner]

What it does

Allows installing VSIX extensions from the file explorer using context menu.

• Contributes a new command that uses selection service to get the *.vsix file instead of opening a dialog
• Adds a @theia/navigator dependency to get the navigator menu ID (existing dependencies like @theia/plugin-ext already depends on the navigator package)
• Refresh 'Installed' tree entries when extension view becomes visible, otherwise one will see updated extension count (badge), but not the new installed entry.
• Other fixes: Added explicit canSelectFiles: true to dialog options, otherwise one can't select files in the electron app. Could be a problem with default handling in ElectronFileDialogService.toOpenDialogOptions()

How to test

Add a *.vsix to your workspace. Use the context menu to execute Install Extension VSIX action. You should see the 'Successfully installed' message. Go to the "Extensions" view and check the "Installed" list contains the new installed extension.

Follow-ups

When testing extension installation I noticed that when installing an already installed extension a Failed to install error is reported. This is because local file deployer rejects installing existing extensions, but because the installing routine can only check the number of installed extension (in this case it's 0) a misleading error is reported.
I think we need to change the installation routine return value to something more meaningful than just a number. With more information we can then to produce a better user feedback. See PluginDeployerImpl.deployPlugins().

Review checklist

• [ x] 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

[martin-fleck-at]

Thank you very much @dhuebner! I think this is a really nice contribution and it works well! I do have a few minor comments regarding naming and visibility, I'd be interested to get your take on that before we merge this change.

[martin-fleck-at]

This works when closing and re-opening the view. Unfortunately it seems that we do not have a notification system for when extensions are deployed, at least none that I can see and implementing one is probably out of scope here.

[dhuebner]

we do not have a notification system for when extensions are deployed

Yeah, I also found nothing there.
An other point I mentioned in the description is that, it would be nice to have an easy way to check if an extension is already installed. And what is even more important, to have a detailed return value when attempting to install an extension. Right now it is just a number of extensions being installed and if it is 0 an error is reported.

[martin-fleck-at]

I fully agree, there is definitely room for improvement on the exposure of extension management. I remember there being a discussion somewhere about being notified properly for uninstallations but I can't find it right now. Do you mind logging a Feature Request for the extension of that API?

[dhuebner]

Sure, will do.

[dhuebner]

@martin-fleck-at
Thank you very much for your review, it was really helpful!
I changed all the related places and think the PR is now even better :)

[dhuebner]

@martin-fleck-at
Are here some remaining changes to be made?
Do you mind to look into my other PR #13344 as well? It is also kind of files related...

[martin-fleck-at]

Thank you very much for the update! Everything looks good to me now!

[martin-fleck-at]

@martin-fleck-at Are here some remaining changes to be made? Do you mind to look into my other PR #13344 as well? It is also kind of files related...

Sure, I can have a look.