[netcore] Propagate ALCs through reflection functions (#16949)

[netcore] Propagate ALCs through reflection functions (#16949)

* [reflection] Pass assembly load context through mono_reflection_get_type_with_rootimage

The entry points are mono_reflection_type_from_name_checked and
mono_reflection_get_type_checked which for now pass in an ambient ALC, but
should be updated to take an ALC argument.

Internally mono_reflection_get_type_with_rootimage is recursive through a half
dozen helper functions which all get an ALC argument too.

The principle place where the ALC is used is in
_mono_reflection_get_type_from_info which passes it to
mono_assembly_loaded_internal and to replace the call to mono_assembly_load by
a direct call to mono_assembly_request_byname with an explicit ALC set in the
request.

* Mark mono_assembly_load as external only

* Pass an alc through non-static reflection functions

* Fix usage in wasm debugger

* Relax assertions due to wasm