Rewrite scheduler context switch code (#1786)

* Rewrite scheduler context switch code

* Fix race in UnmapIpcRestorePermission

* Fix thread exit issue that could leave the scheduler in a invalid state

* Change context switch method to not wait on guest thread, remove spin wait, use SignalAndWait to pass control

* Remove multi-core setting (it is always on now)

* Re-enable assert

* Remove multicore from default config and schema

* Fix race in KTimeManager

Ryujinx/_schema.json

@@ -18,7 +18,6 @@
     "system_region",
     "docked_mode",
     "enable_vsync",
-    "enable_multicore_scheduling",
     "enable_ptc",
     "enable_fs_integrity_checks",
     "fs_global_access_log_mode",
@@ -1196,17 +1195,6 @@
         false
       ]
     },
-    "enable_multicore_scheduling": {
-      "$id": "#/properties/enable_multicore_scheduling",
-      "type": "boolean",
-      "title": "Enable Multicore Scheduling",
-      "description": "Enables or disables multi-core scheduling of threads",
-      "default": true,
-      "examples": [
-        true,
-        false
-      ]
-    },
     "enable_ptc": {
       "$id": "#/properties/enable_ptc",
       "type": "boolean",