Standalone mode for viewer (self build)

[elliottslaughter]

Similar to #64, except it runs the Trunk build directly.

This hits a deadlock because the Cargo lock on the build is already taken:

[legion_prof_viewer 0.3.0]     Blocking waiting for file lock on build directory
Building [=======================> ] 205/208: legion_prof_viewer(build)

Unless the deadlock can be fixed, this is a dead end.