images.Text: Add "alignx" option for horizontal alignment

Add an "alignx" option to the images.Text to control whether the value of the "x" option is the left border of the text (current behaviour), the center of each line or the right border.

Fixes #10849

content/en/functions/images/Text.md

@@ -37,6 +37,10 @@ x
 y
 : (`int`) The vertical offset, in pixels, relative to the top of the image. Default is `10`.
 
+alignx
+ {{< new-in 0.141.0 >}}
+: (`string`) The horizontal alignment of the text relative to the `x` position. One of `left`, `center`, or `right`. Default is `left`.
+
 [global resource]: /getting-started/glossary/#global-resource
 [page resource]: /getting-started/glossary/#page-resource
 [remote resource]: /getting-started/glossary/#remote-resource