[Bug #19896]

	fix memory leak in vm_method

	This introduces a unified reference_count to clarify who is referencing a method.
	This also allows us to treat the refinement method as the def owner since it counts itself as a reference

Co-authored-by: Peter Zhu <peter@peterzhu.ca>
	---
	 gc.c                     |   4 +-
	 method.h                 |   6 +--
	 rjit_c.rb                |   6 +--
	 test/ruby/test_module.rb |   4 +-
	 vm_insnhelper.c          |   2 +-
	 vm_method.c              | 105 +++++++++++++++++++----------------------------
	 6 files changed, 54 insertions(+), 73 deletions(-)