outline_panel: Rename outline_panel::Open to outline_panel::OpenSelectedEntry (#28890)

Closes #27171

The `outline_panel::Open` action seems to open the outline panel, but
instead, it moves the editor's cursor to the position of the selected
entry in the outline panel. This PR renames it to
`outline_panel::OpenSelectedEntry` for better clarity.

Meanwhile, there is an existing action, `outline_panel::ToggleFocus`,
that should be used for opening the outline panel.

Todo:
- [x] Added migration

Release Notes:

- Renamed `outline_panel::Open` to `outline_panel::OpenSelectedEntry`
for better clarity.

crates/migrator/src/migrations.rs

@@ -39,7 +39,9 @@ pub(crate) mod m_2025_03_29 {
 }
 
 pub(crate) mod m_2025_04_15 {
+    mod keymap;
     mod settings;
 
+    pub(crate) use keymap::KEYMAP_PATTERNS;
     pub(crate) use settings::SETTINGS_PATTERNS;
 }