Peritext rendering surface UI improvements

[streamich]

• Ability to provide custom renderers for all elements.
  • Caret
  • Selection anchor
  • Selection focus
  • Selection body
  • Inline
  • Leaf block
  • Block
  • Whole document
• Ability to compose many renderer maps together.
• Ability to add custom events.
• Handle soft line navigation.
  • Detect soft line wrap boundaries.
• Ability to provide suggestions, inlay hints.
  • Spellcheking
  • Integration with LLM
• Add concept of blurred cursor. The cursor becomes grey when editor loses focus, when editor regains focus, the starting cursor position is where the blurred cursor was left.
• When navigating with ArrowLeft and ArrowRight, allow to move half-point, i.e. one Peritext point unit, which is not necessarily skipping a whole character. Instead, when pressing RightArrow, it could move from the After anchor of the current character to Before anchor of the next character.
• In multi-cursor setting, when cursor selections (or carets) overlap, join the cursors.
• Support for autocompletion popups.
• cursor event
  • Fix selection mouse down behavior.
  • Support model-space locations Point<T>.
  • Cleanup CursorDetail, len should just be number.
• Narrow down DOM controller depedency types, pick only what is necessary from event objects.
• In all cursor edges, in view, render the side specifying to which character anchor point the cursor is attached.
• Rename both cursor to caret.
• Add ability to compute .hash for Inline nodes and use that for memoization.
• Reset pressed key on window resize, this will handle Devtools open event.