refactor(options): autogenerate valid values and flag enums for options (#31089)

Problem: Option metadata like list of valid values for an option and
option flags are not listed in the `options.lua` file and are instead
manually defined in C, which means option metadata is split between
several places.

Solution: Put metadata such as list of valid values for an option and
option flags in `options.lua`, and autogenerate the corresponding C
variables and enums.

Supersedes #28659

Co-authored-by: glepnir <glephunter@gmail.com>

src/nvim/undo.c

@@ -2528,7 +2528,7 @@ static void u_undoredo(bool undo, bool do_buf_event)
 /// @param absolute  used ":undo N"
 static void u_undo_end(bool did_undo, bool absolute, bool quiet)
 {
-  if ((fdo_flags & FDO_UNDO) && KeyTyped) {
+  if ((fdo_flags & kOptFdoFlagUndo) && KeyTyped) {
     foldOpenCursor();
   }