* pgl: add skeleton folder to stratosphere

* pgl: Add service interface for IShellInterface

* pgl: begin skeletoning shell service, implement two commands.

* pgl: Implement three more commands.

* pgl: implement bool tracking commands

* pgl: Implement TriggerApplicationSnapShotDumper

* pgl: implement InitializeProcessControlTask

* pgl: Implement pgl::srv::Initialize

* pgl: Implement main()

* pgl: Implement (Get)ShellEventObserver

* pgl: implement LaunchProgramFromHost, GetHostContentMetaInfo

* pgl: Implement ProcessControlTask

* settings: fix duplicate object name

* pgl: fix minor bugs in impl

This was tested using `https://github.com/node-dot-cpp/alloc-test` plus a few other by-hand tests.

It seems to work for the case we care about (sysmodules without thread cache-ing).

External users are advised to build with assertions on and contact SciresM if you find issues.

This is a lot of code to have gotten right in one go, and it was written mostly after midnight while sick, so there are probably un-noticed issues.