Modifier ψ and ω

[eggrobin]

See https://github.com/unicode-org/sah/issues/485 and L2/24-145, Unicode request for modifier psi and omega.

UTC-180-C34 Consensus: Provisionally assign two modifier letter code points U+1DFF3 MODIFIER LETTER SMALL GREEK PSI, U+1DFF4 MODIFIER LETTER SMALL GREEK OMEGA in the Latin Extended-G block as described in L2/24-145R [Ref. Section 13 of document L2/24-166]

https://github.com/unicode-org/utc-release-management/issues/127

[eggrobin]

@markusicu Note that we reviewed this with incorrect names (from the non-R version of the document).
Now corrected, and I updated the tests to use a similarly named character as a reference and to explicitly mention its name.
I don’t think there is much more I can reliably do to prevent that kind of error from my side, I added a note to the RMG agenda so that these updates don’t get dropped on the floor.