Fix handling of medial hyphens in Unicode Names.

In a Unicode name was stored in a way that caused
a medial hyphen to be at the end of a a chunk, it would not
be properly ignored by the loose matching algorithm.

For example if `LEFT-TO-RIGHT OVERRIDE` was stored as
`LEFT-` [...], the `-` would not be ignored.

The generators now ensures nodes are not cut accross
medial hyphen boundaries.

Fixes #64161

Differential Revision: https://reviews.llvm.org/D156518