[176-C26] Consensus: Add a new informative derived enumerated property Indic_Conjunct_Break (InCB) to DerivedCoreProperties.txt, with values Linker, Consonant, and Extend that correspond respectively to the macros ConjunctLinker, LinkingConsonant, and ExtCccZwj from draft 2 of the the Proposed Update to Unicode Standard Annex #‌29, Unicode Text Segmentation, and with a default value of None (None), for Unicode Version 15.1.

[176-A87] Action Item for Robin Leroy, PAG: Add the new enumerated property Indic_Conjunct_Break (InCB), with values Linker, Consonant, and Extend to PropertyAliases.txt, PropertyValueAliases.txt, and DerivedCoreProperties.txt, for Unicode Version 15.1. See document L2/23-160 item 4.3.

Plus the unicodetools side of

[176-A88] Action Item for Josh Hadley, PAG: Update rule GB9c Unicode Standard Annex #‌29, Unicode Text Segmentation, to use the Indic_Conjunct_Break property instead of macros, for Unicode Version 15.1. See document L2/23-160 item 4.3.

Notes:

1. The property definitions are as amended in discussion and as written by Ken into the working draft of UAX44.
2. The tests are generated by setting ExtCccZwj to the union of InCB=Extend and InCB=Linker, as discussed.
3. There is a new test case for consonant-virama-virama-consonant at the bottom of GraphemeBreakTest; if we replaced ExtCccZwj by InCB=Extend, the behaviour would change for that test, see eggrobin@cb57b44.