Recognise (and potentially highlight) roles of interpreted text

[ghost]

It would be nice if roles like ":role:text" and text:role:" [1] would be recognised by this syntax plugin.
This would allow syntax highlighting and spell checking (see #12).

Notes:

• Valid role names "conform to the rules of simple reference names" [2].
• Roles can be pre- (":role:text") or post (text:role:")
• Be aware that Sphinx has "domains" whose roles contain a colon, e.g. ":py:role:text". This should also be supported (should be covered by [2] but want to point it out due to the internal colon and its wide-spread usage).
• Be aware that the :text: syntax is also used in field lists.

[1] https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#interpreted-text
[2] https://docutils.sourceforge.io/docs/ref/rst/directives.html#role-name