add utility the emphasize case insensitive portions of strings (#810)

Sources/Site/Utility/String+EmphasizedMatching.swift

@@ -0,0 +1,25 @@
+//
+//  String+EmphasizedMatching.swift
+//
+//
+//  Created by Greg Bolsinga on 6/15/24.
+//
+
+import Foundation
+import RegexBuilder
+
+extension String {
+  func emphasized(matching fragment: String) -> String {
+    let regex = Regex {
+      Capture {
+        fragment
+      }
+    }
+    .ignoresCase()
+
+    return self.replacing(regex, maxReplacements: 1) {
+      let (_, m) = $0.output
+      return "**\(m)**"
+    }
+  }
+}

Tests/SiteTests/EmphasizedMatchingTests.swift

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+//
+//  EmphasizedMatchingTests.swift
+//
+//
+//  Created by Greg Bolsinga on 6/15/24.
+//
+
+import XCTest
+
+@testable import Site
+
+final class EmphasizedMatchingTests: XCTestCase {
+  func testJustOneLetterMatchingWithOneMatch() throws {
+    XCTAssertEqual("Gre".emphasized(matching: "G"), "**G**re")
+    XCTAssertEqual("Gre".emphasized(matching: "g"), "**G**re")
+  }
+
+  func testJustOneLetterMatchinWithMultipleMatches() throws {
+    XCTAssertEqual("Greg".emphasized(matching: "G"), "**G**reg")
+    XCTAssertEqual("Greg".emphasized(matching: "g"), "**G**reg")
+  }
+
+  func testTwoLettersMatchingWithOneMatch() throws {
+    XCTAssertEqual("Greg".emphasized(matching: "Gr"), "**Gr**eg")
+    XCTAssertEqual("Greg".emphasized(matching: "gr"), "**Gr**eg")
+  }
+
+  func testTwoLettersMatchingWithMultipleMatches() throws {
+    XCTAssertEqual("Gregr".emphasized(matching: "Gr"), "**Gr**egr")
+    XCTAssertEqual("GregR".emphasized(matching: "gr"), "**Gr**egR")
+  }
+}