Package theia-trace-extension for linux distros and other

[tahini]

It should be easy for users to install and run the theia-trace-extension and trace server.

We should look at how other nodejs applications do, like vscode. For ubuntu, snap can be used

[marcdumais-work]

With #74 we have a base: an Electron builder config was added, that can be used to produce end-user packages for the example application. ATM it supports Linux packaging (AppImage and Debian packages).

Windows and Mac packaging are also possible, but IIUC require signing so the end-users can install them without security warnings.

See the following theia-apps PR, where Travis CI is used to produce and make available packages for an Electron example application. The plan for the main Eclipse Theia project is to use the Eclipse Foundation signing service.

theia-ide/theia-apps#370
Corresponding wiki entry: https://github.com/theia-ide/theia-apps/wiki/Publishing-a-release
Released packages: https://github.com/theia-ide/theia-apps/releases (note: I am not 100% happy with a name such as "Theia-1.2.0.AppImage" - I'll correct at some point to add "example" in there)

[marcdumais-work]

Note: I think this applies to the example app - the issue title seems to refer to the extension, not the app. The extension should also be packaged and published, but in the form of a npm package.

[MatthewKhouzam]

@arfio Is this what you progressed on by making the appimage?

[arfio]

well, I did a pull request, but other changes were needed so there was a pull request by paul #594.