Completely rethink R:I:JSON.str-escapes
Completely rethink R:I:JSON.str-escapes

- makes to-json about 2x as fast for a stucture from a 5MB JSON
- uses decomposed NFD instead of regular expressions
- creates fast path for common ASCII characters
- also optimize tear-off-combiners and to-surrogate-pair
- also reduces core size by about 11MB

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