Add ref.any warning sub-type

[simaoafonso-pwt]

Subject: Allow for suppression of ambigous "any" xref warnings

Feature or Bugfix

• Feature

Purpose

• To allow supressing the ambigous "any" cross-reference warning, mark it with a "ref.any" marker.

Detail

• This should decrease the amount of spurious warnings, but I agree it should not be enabled by default.

Relates

• more than one target found for cross reference should prefer current file's method over other libraries methods #4961

[AA-Turner]

This would need an entry in the suppress_warnings list and an entry in CHANGES.rst. Several other warning types have been added recently, for inspiration.

A