Fix indentation for c-ts-mode (bug#61026)

Fix indentation for c-ts-mode (bug#61026)

Fix indentation for things like

  while (true)
    if (true)
      {
        puts ("Hello");
      }

Note that the outer while loop omits brackets.

* lisp/progmodes/c-ts-mode.el:
(c-ts-mode--statement-offset-post-processr): New variable.
(c-ts-mode--statement-offset): Use the new function.
(c-ts-mode--fix-bracketless-indent): New function.
(c-ts-base-mode): Use the new function.
* test/lisp/progmodes/c-ts-mode-resources/indent.erts: New tests.