(WIP) Refactor: Remove AVM

[hikettei]

• Make the process of adding a new accelerator sophisticated and simple!
  • Add BACKEND=LISP
  • Add BACKEND=LISPJIT
  • Move codegen stuff to byoc (BACKEND=CLANG)
  • Add BACKEND=METAL (Fine if CI fails)
  • Bring back JIT
• Create caten/runtime, a refactored version of AVM
• Remove AVM
• git grep "avm" -> nothing?
• git grep "JIT" -> nothing?
• git grep "JIT_BACKEND" -> nothing?
• Move backends from caten/backends ... to caten/byoc ...
• define-backend TODO: define-byoc (register an keyword to Renderer, Runtime, Buffer, AutoScheduler, whether JIT=1 or JIT=0 runtime)
• update ./docs/examples
• update documents
• update readme
• JIT=1, JIT_BACKEND is removed
• update test-suite
• AOT_VERBOSE is removed
• AOT is removed
• AOT_VM is removed
• Refactor: Move caten/nn.test -> caten/test-suite #370
• Move everything into caten/test-suite
• Remove dump method
• update ci args