Make OrbitApp::LoadPreset use LoadPresetModule
Make OrbitApp::LoadPreset use LoadPresetModule

LoadPreset is now basically a loop over `LoadPresetModule`. All the work
that concerns a single module (loading symbols, hooking functions,
enabling frame tracks) happens in `LoadPresetModule`.

`LoadPreset` will still take care of showing an error dialog to the user
if something couldn't be loaded.

google/orbit,google/orbit,google/orbit,google/orbit