images: Add option for vertical alignment to images.Text

images: Add option for vertical alignment to images.Text

Add option ``aligny`` to specify the vertical alignment of the text
with respect to the ``y`` offset from the top of the image. Possible
values of ``aligny`` are ``top`` (default), ``center``, and ``bottom``.

The height of the block of text is measured from the top of the first
line to the baseline of the last line.

- ``top``: (Current behaviour) The top of the first line of the block of
  text is at an offset of ``y`` from the top of the image.

- ``center``: The vertical center of the block of text is at an offset of
  ``y`` from the top of the image.

- ``bottom``: The baseline of the last line of the text is at an offset
  of ``y`` from the top of the image.

Resolves #13414