[reflection] Use mono_module_get_object_handle everywhere (#4010)

[reflection] Use mono_module_get_object_handle everywhere (#4010)

* [reflection] Refactor managed object caching

Split up all the mono_XXX_get_object_checked functions into a generic
cache check and a specific construction function that's called if
there's a cache miss.

* [reflection] Add mono_assembly_get_object_handle

* [reflection] Add mono_module_get_object_handle

* [reflection] Use mono_module_get_object_handle everywhere

instead of mono_module_get_object_checked.

Also implement mono_module_file_get_object_handle instead of mono_module_file_get_object_checked