build: ship "_core/*" as bytecode (built-into Nvim binary)

Problem:
We want to encourage implementing core features in Lua instead of C, but
it's clumsy because:
- Core Lua code (built into `nvim` so it is available even if VIMRUNTIME
  is missing/invalid) requires manually updating CMakeLists.txt, or
  stuffing it into `_editor.lua`.
- Core Lua modules are not organized similar to C modules, `_editor.lua`
  is getting too big.

Solution:
- Introduce `_core/` where core Lua code can live. All Lua modules added
  there will automatically be included as bytecode in the `nvim` binary.
- Move these core modules into `_core/*`:
  ```
  _defaults.lua
  _editor.lua
  _options.lua
  _system.lua
  shared.lua
  ```

TODO:
- Move `_extui/ => _core/ui2/`

1 files changed, 4 insertions, 4 deletions

diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 4073e0f9a8..181a549e23 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -2137,8 +2137,8 @@ void nlua_set_sctx(sctx_T *current)
   // Files where internal wrappers are defined so we can ignore them
   // like vim.o/opt etc are defined in _options.lua
   char *ignorelist[] = {
-    "vim/_editor.lua",
-    "vim/_options.lua",
+    "vim/_core/editor.lua",
+    "vim/_core/options.lua",
     "vim/keymap.lua",
   };
   int ignorelist_size = sizeof(ignorelist) / sizeof(ignorelist[0]);
@@ -2404,14 +2404,14 @@ plain: {}
   return arena_printf(arena, "<Lua %d>", ref).data;
 }
 
-/// Execute the vim._defaults module to set up default mappings and autocommands
+/// Execute the vim._core.defaults module to set up default mappings and autocommands
 void nlua_init_defaults(void)
 {
   lua_State *const L = global_lstate;
   assert(L);
 
   lua_getglobal(L, "require");
-  lua_pushstring(L, "vim._defaults");
+  lua_pushstring(L, "vim._core.defaults");
   if (nlua_pcall(L, 1, 0)) {
     fprintf(stderr, "%s\n", lua_tostring(L, -1));
   }