fix(style): some clang-tidy 22 fixes

CI currently uses clang-tidy 20, but this affects local builds
and CI is going to be upgraded sooner or later.

Some remaining systematic issues:

- clang-tidy warns agains any atoi() or atol() usage (because of no
  error handling)

- functions which takes (char *fmt, char *only_string_arg) and expect
  fmt to contain exactly one "%s" usage.

- error: initializing non-local variable with non-const expression depending on
  uninitialized non-local variable (cppcoreguidelines-interfaces-global-init)

  This is a much worse problem in C++ (hence C++ core guidelines) where
  initialization is intermingled with arbitrary code execution. I
  "think" in plain C, the linker will either resolve all these
  deterministically or barf an error. But with some restructuring
  we could make all static initialization actually static..

src/nvim/lua/converter.c

@@ -731,7 +731,7 @@ void nlua_push_Array(lua_State *lstate, const Array array, int flags)
 void nlua_push_handle(lua_State *lstate, const handle_T item, int flags)
   FUNC_ATTR_NONNULL_ALL
 {
-  lua_pushnumber(lstate, (lua_Number)(item));
+  lua_pushnumber(lstate, (lua_Number)item);
 }
 
 /// Convert given Object to Lua value