* Bump %unicode 9 -> %unicode 12.1 for the 3 unicode grammars
* regenerate emoji conformance tests for unicode 12.1
* modify wordbreak conformance tests to use emoji data (which replaces old crazy E_base etc properties)
* regenerate wordbreak conformance tests
* Simplify grammar files and word-break conformance test generator, now that full-width numbers are WordBreak=Numeric
* Use jflex emoji properties rather than ICU-generated ones
* LUCENE-9909: Some jflex regeneration tasks should have proper dependencies and also check the checksums of included files.
* Force a dependency on low-level spotless tasks so that they're always properly ordered (hell!). Update ASCIITLD and regenerate the remaining code. Add cross-dependencies between generation tasks that take includes as input.
The compilation of the library is slow, disable optimization as it doesn't speed up our usage of the gennorm2 tool.
Use better heuristic for make parallelism (tests.jvms rather than just hardcoded value of four).
Upgrade from icu 62.2 to 68.2, with Unicode 13 support.
Modify GenerateUTR30DataFiles to take the release tag as a program
argument. Gradle populates this automatically, removing a manual step
from regeneration process.
