[runtime] Use coop handles for the remaining System.Reflection.Assembly icalls (...

[runtime] Use coop handles for the remaining System.Reflection.Assembly icalls (#4082)

* [reflection] Use handles for System.Reflection.Assembly.GetFilesInternal

* [reflection] Use handles for System.Reflection.Assembly.InternalGetType

* [reflection] Use handles for System.Reflection.Assembly.GetManifestResourceNames

* [reflection] Use handles for System.Reflection.Assembly.LoadPermissions

* [reflection] Add mono_method_get_object_handle

  Reimplement mono_method_get_object_checked in terms of the handles one.

* [reflection] Use handles for System.Reflection.Assembly.get_EntryPoint

* [reflection] Use handles for four more icalls in System.Refleciton.Assembly

  That's the lot of them.

    * get_ReflecitonOnly
    * get_code_base
    * get_fullname

* get_global_assembly_cache

* [security] Use handles for System.Security.Policy.Evidence.IsAuthenticodePresent

* [runtime] Use handles for System.Web.Util.Icalls.GetUnmanagedResourcesPtr

* [runtime] Use MONO_HANDLE_GETVAL instead of MONO_HANDLE_RAW in a few places

* [runtime] Use handles for System.AppDomain.ExecuteAssembly