Support relative line number on wrapped lines (#39268)

**Problem:** Current relative line numbering creates a mismatch with
vim-style navigation when soft wrap is enabled. Users must mentally
calculate whether target lines are wrapped segments or logical lines,
making `<n>j/k` navigation unreliable and cognitively demanding.

**How things work today:**
- Real line navigation (`j/k` moves by logical lines): Requires
determining if visible lines are wrapped segments before jumping. Can't
jump to wrapped lines directly.
- Display line navigation (`j/k` moves by display rows): Line numbers
don't correspond to actual row distances for multi-line jumps.

**Proposed solution:** Count and number each display line (including
wrapped segments) for relative numbering. This creates direct
visual-to-navigational correspondence where the relative number shown
always matches the `<n>j/k` distance needed.

**Benefits:**
- Eliminates mental overhead of distinguishing wrapped vs. logical lines
- Makes relative line numbers consistently actionable regardless of wrap
state
- Preserves intuitive "what you see is what you navigate" principle
- Maintains vim workflow efficiency in narrow window scenarios

Also explained an discussed in
https://github.com/zed-industries/zed/discussions/25733.

Release Notes:

Release Notes:

- Added support for counting wrapped lines as relative lines and for
displaying line numbers for wrapped segments. Changes
`relative_line_numbers` from a boolean to an enum: `enabled`,
`disabled`, or `wrapped`.

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

docs/src/visual-customization.md

@@ -204,7 +204,7 @@ TBD: Centered layout related settings
     "folds": true,                // Show/hide show fold buttons in the gutter.
     "min_line_number_digits": 4   // Reserve space for N digit line numbers
   },
-  "relative_line_numbers": false, // Show relative line numbers in gutter
+  "relative_line_numbers": "enabled", // Show relative line numbers in gutter
 
   // Indent guides
   "indent_guides": {