perf: don't use regex in trim_{prefix,suffix}

regex is overkill for this, and performance is quite bad

Fixes: b131c74ee3 ("Add prefix and suffix string trimming functions")
Signed-off-by: William Casarin <jb55@jb55.com>

damusTests/Benchmarking.swift

@@ -0,0 +1,72 @@
+//
+//  Benchmarking.swift
+//  damusTests
+//
+//  Created by William Casarin on 3/6/25.
+//
+
+import Testing
+import XCTest
+@testable import damus
+
+class BenchmarkingTests: XCTestCase {
+    
+    // Old regex-based implementations for comparison
+    func trim_suffix_regex(_ str: String) -> String {
+        return str.replacingOccurrences(of: "\\s+$", with: "", options: .regularExpression)
+    }
+    
+    func trim_prefix_regex(_ str: String) -> String {
+        return str.replacingOccurrences(of: "^\\s+", with: "", options: .regularExpression)
+    }
+    
+    // Test strings with different characteristics
+    lazy var testStrings: [String] = [
+        "   Hello World   ",                                // Simple whitespace
+        "   \n\t  Hello World \n\t   ",                     // Mixed whitespace
+        String(repeating: " ", count: 1000) + "Hello",      // Large prefix
+        "Hello" + String(repeating: " ", count: 1000),      // Large suffix
+        String(repeating: " ", count: 500) + "Hello" + String(repeating: " ", count: 500) // Both
+    ]
+    
+    func testTrimSuffixRegexPerformance() throws {
+        measure {
+            for str in testStrings {
+                _ = trim_suffix_regex(str)
+            }
+        }
+    }
+    
+    func testTrimSuffixNewPerformance() throws {
+        measure {
+            for str in testStrings {
+                _ = trim_suffix(str)
+            }
+        }
+    }
+    
+    func testTrimPrefixRegexPerformance() throws {
+        measure {
+            for str in testStrings {
+                _ = trim_prefix_regex(str)
+            }
+        }
+    }
+    
+    func testTrimPrefixNewPerformance() throws {
+        measure {
+            for str in testStrings {
+                _ = trim_prefix(str)
+            }
+        }
+    }
+    
+    func testTrimFunctionCorrectness() throws {
+        // Verify that both implementations produce the same results
+        for str in testStrings {
+            XCTAssertEqual(trim_suffix(str), trim_suffix_regex(str), "New trim_suffix implementation produces different results")
+            XCTAssertEqual(trim_prefix(str), trim_prefix_regex(str), "New trim_prefix implementation produces different results")
+        }
+    }
+}
+