Provide way to install a trace server

[bhufmann]

Right now, a trace server needs to be started / configured manually by the user of an Theia application that has the theia-traceviewer installed. Preferences exits to configure the executable path and the command-line parameter.

It would be good to be able to install a trace server implementation to the Theia application, i.e. through an OpenVsx extension. This will bundle the trace server application, sets the path as well as configures the command-line parameters for that instance.

This is similar to installing language servers or debug adapters to the application.

Note that the implementation in the theia-traceviewer needs to be able to handle multiple different trace server installations from OpenVsx (e.g. make sure that user is notified to select one, have a list of available servers in the preference page)