Support relative line number on wrapped lines (rework) (#41805)

## Add relative line numbers on wrapped lines, take 2

This is a rework of https://github.com/zed-industries/zed/pull/39268
that excludes
https://github.com/zed-industries/zed/pull/39268/commits/e7096d27a6463f6eb7c2a821637c5773b2460c10.
This commit introduced some line number rendering issues as described in
https://github.com/zed-industries/zed/issues/41422.

While @ConradIrwin suggested we try to pass in the buffer rows from the
calling method instead of the snapshot, that
appears to have had unintended consequences and I don't think the two
calculations were intended to do the same thing. Hence, this PR has
removed those changes.

This PR also includes the migration fix originally done by @MrSubidubi
in https://github.com/zed-industries/zed/pull/41351.

## Original PR description and release notes.

**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 and discussed in
https://github.com/zed-industries/zed/discussions/25733.

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`.

crates/settings/src/settings_content/editor.rs

@@ -97,9 +97,11 @@ pub struct EditorSettingsContent {
     #[serde(serialize_with = "crate::serialize_optional_f32_with_two_decimal_places")]
     pub fast_scroll_sensitivity: Option<f32>,
     /// Whether the line numbers on editors gutter are relative or not.
+    /// When "enabled" shows relative number of buffer lines, when "wrapped" shows
+    /// relative number of display lines.
     ///
-    /// Default: false
-    pub relative_line_numbers: Option<bool>,
+    /// Default: "disabled"
+    pub relative_line_numbers: Option<RelativeLineNumbers>,
     /// When to populate a new search's query based on the text under the cursor.
     ///
     /// Default: always
@@ -212,6 +214,41 @@ pub struct EditorSettingsContent {
     pub completion_menu_scrollbar: Option<ShowScrollbar>,
 }
 
+#[derive(
+    Debug,
+    Clone,
+    Copy,
+    Serialize,
+    Deserialize,
+    JsonSchema,
+    MergeFrom,
+    PartialEq,
+    Eq,
+    strum::VariantArray,
+    strum::VariantNames,
+)]
+#[serde(rename_all = "snake_case")]
+pub enum RelativeLineNumbers {
+    Disabled,
+    Enabled,
+    Wrapped,
+}
+
+impl RelativeLineNumbers {
+    pub fn enabled(&self) -> bool {
+        match self {
+            RelativeLineNumbers::Enabled | RelativeLineNumbers::Wrapped => true,
+            RelativeLineNumbers::Disabled => false,
+        }
+    }
+    pub fn wrapped(&self) -> bool {
+        match self {
+            RelativeLineNumbers::Enabled | RelativeLineNumbers::Disabled => false,
+            RelativeLineNumbers::Wrapped => true,
+        }
+    }
+}
+
 // Toolbar related settings
 #[skip_serializing_none]
 #[derive(Debug, Clone, Default, Serialize, Deserialize, JsonSchema, MergeFrom, PartialEq, Eq)]

crates/settings/src/vscode_import.rs

@@ -275,7 +275,7 @@ impl VsCodeSettings {
             }),
             redact_private_values: None,
             relative_line_numbers: self.read_enum("editor.lineNumbers", |s| match s {
-                "relative" => Some(true),
+                "relative" => Some(RelativeLineNumbers::Enabled),
                 _ => None,
             }),
             rounded_selection: self.read_bool("editor.roundedSelection"),