vim: Add smartcase search (#16932)

Closes #16878

Release Notes:

- Added a vim-style smart case option for search patterns

---------

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

crates/editor/src/editor_settings.rs

@@ -20,6 +20,7 @@ pub struct EditorSettings {
     pub scroll_sensitivity: f32,
     pub relative_line_numbers: bool,
     pub seed_search_query_from_cursor: SeedQuerySetting,
+    pub use_smartcase_search: bool,
     pub multi_cursor_modifier: MultiCursorModifier,
     pub redact_private_values: bool,
     pub expand_excerpt_lines: u32,
@@ -218,6 +219,7 @@ pub struct EditorSettingsContent {
     ///
     /// Default: always
     pub seed_search_query_from_cursor: Option<SeedQuerySetting>,
+    pub use_smartcase_search: Option<bool>,
     /// The key to use for adding multiple cursors
     ///
     /// Default: alt