AOT Refactor

[abcdabcd987]

Tracking ticket for the implementation of unifying JIT and AOT code path (#791).

High level approach:

1. Capture the building instructions for each torch cpp extension in a JitSpec object.
2. Generate ninja file for each JitSpec. Notably, the output target should be $name/$name.so, i.e., including the name of the torch cpp extension.
3. Generate a wrapper ninja file that use subninja to include all ninja files.
4. After building all torch cpp extensions, copy the .so files to data/aot/ and ship the package.

Tasks:

• JitSpec and Generate ninja file. misc: jit: Introduce JitSpec and Generate ninja file #1065
  • bugfix for _get_glibcxx_abi_build_flags misc: jit: fix missing _get_glibcxx_abi_build_flags #1080
• Remove load_cuda_ops(). misc: jit: Deprecate load_cuda_ops() #1066
• Refactor to let all modules to return JitSpec. misc: jit: Refactor gen JitSpec out of get_xxx_module #1069
• Replace parallel_load_modules() with build_jit_specs(). misc: jit: Replace parallel_load_modules() with build_jit_specs() #1070
• Override workspace dir. misc: jit: Import jit_env as a module #1073
• Script to build all AOT ops. misc: aot: Add script to build all AOT ops #1067
• Packaging. misc: aot: Refactor AOT packaging #1075
• Remove has_prebuilt_ops. misc: aot: Remove has_prebuilt_ops #1076
• Use /dev/shm for lock.