Make example applications more like trace viewer appliances

[marcdumais-work]

In #1071, we removed content from the example applications, that's not deemed necessary for using these apps for the purpose of testing in this repo. Since we use the example apps to test the "theia trace extension", they did not need to have extra features, like support running vscode extensions. This makes for leaner apps, that build quicker, so quicker CI, etc.

If it's desired to make the test apps (or other Theia apps that use "theia trace extension") even more appliance-like, it would be possible to remove some unneeded Theia framework contributions, like the problems and outline views, as well as e.g. menu entries that do not bring much value for a trace viewer appliance.

One way to do so would be to use Theia's "registerContributionFilters", like in this example from Vincent F:
https://github.com/vince-fugnitto/theia-no-debug/blob/master/no-debug/src/browser/no-debug-contribution.ts

This filtering would not be suitable for the case where the Theia trace extension is used in a full-fledge IDE, only for an appliance. As such, the filterring would need to be done in a separate Theia extension, that would only be included in appliances. e.g. named something like "trace-viewer-appliance".

Some potential items:

• have the trace viewer expanded at startup (equivalent to when clicking on the left-panel "Trace Viewer" entry
• Programmatically remove remaining un-needed Theia framework contributions:
  • Problems view
  • Outline view
  • misc menus/menu entries
  • etc...