Changes for #158941

[encukou]

See python#158941

• The Sphinx extension should distinguish between const and macro (see the comment in stable_abi.toml for what that means). So, expose "kind" in Doc/data/stable_abi.dat, instead of the ReST role.
• Fix kind of PY_VECTORCALL_ARGUMENTS_OFFSET: it's just a number
• Make it explicit that (function-like) macros aren't part of the Stable ABI. They're part of the (C-only) Limited API.
  • Some people (rightfully) complain that the terms "Stable ABI" vs. "Limited API" are confusing, so instead of "Limited API" I prefer "available when compiling for Stable ABI" in new docs.
• Per-item data should be in the TOML file. Move STATIC_INLINE_FUNCTIONS there.

[vstinner]

Merged, thanks.