Rename "find" to "search"

Search is both a verb and a noun, which makes it more natural to use in situations where we need to name a thing rather than a process.

crates/search/src/search.rs

@@ -0,0 +1,16 @@
+use gpui::MutableAppContext;
+
+mod buffer_search;
+mod project_search;
+
+pub fn init(cx: &mut MutableAppContext) {
+    buffer_search::init(cx);
+    project_search::init(cx);
+}
+
+#[derive(Clone, Copy)]
+pub enum SearchOption {
+    WholeWord,
+    CaseSensitive,
+    Regex,
+}