feat: hires boundary

[bluwy]

hires: 'boundary' generates a segment for each word boundary, instead of for each character. Which should help:

• Reduce sourcemap size
• Easier to find original position in mappings
• Faster sourcemap merging

From twitter idea: https://twitter.com/dummdidumm_/status/1674102437890621454

Example sourcemap visualization

[lforst]

This PR is the next best thing since sliced bread. <3