The current strategy of searching for a code point within the generated
table is slow for code points > U+0377 (the last code point whose index
is the same value as the code point itself). For larger code points, we
are doing a linear search through the table.
Instead, generate a HashMap of each code point to its entry in the table
for faster runtime lookups.
This had the added benefit of being able to remove a fair amount of code
from the generator. We no longer need to track that last contiguous code
point (U+0377) nor each code point's index in the generated table.
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