org-element: Update property drawers parsing

org-element: Update property drawers parsing

* lisp/org-element.el (org-element--get-node-properties,
  org-element--get-time-properties): New functions.
(org-element-headline-parser, org-element-inlinetask-parser): Use new
functions.
(org-element-property-drawer-parser): Change signature.  Simplify
parsing.
drawer.
(org-element--current-element, org-element--next-mode): Property
drawers are located right after a headline or a planning element.

* testing/lisp/test-org-element.el (test-org-element/drawer-parser,
  test-org-element/node-property,
  test-org-element/property-drawer-interpreter): Update tests.
(test-org-element/property-drawer-parser): Add tests.
* testing/lisp/test-org.el (test-org/indent-line,
  test-org/indent-region, test-org/forward-paragraph,
  test-org/backward-paragraph): Update tests.