refactor: format all C files under nvim/ #15977

* refactor: format all C files under nvim
* refactor: disable formatting for Vim-owned files:
    * src/nvim/indent_c.c
    * src/nvim/regexp.c
    * src/nvim/regexp_nfa.c
    * src/nvim/testdir/samples/memfile_test.c

src/nvim/api/vim.c

@@ -2846,7 +2846,7 @@ Array nvim_get_mark(String name, Error *err)
     bufnr = mark.fmark.fnum;
     filename = (char *)buflist_nr2name(bufnr, true, true);
     allocated = true;
-  // Marks comes from shada
+    // Marks comes from shada
   } else {
     filename = (char *)mark.fname;
     bufnr = 0;