Update the default logs directory and allow collection from elsewhere. (#4352)

* Replace deprecated URL methods.

* Start putting log files in Library/Logs (moving existing files with a migration.)

* Make Tracing.deleteLogFiles aware of the legacy logs location.

* Allow the logs to be collected from a different directory.

UnitTests/Sources/LoggingTests.swift

@@ -17,7 +17,7 @@ class LoggingTests: XCTestCase {
     }
 
     override func setUpWithError() throws {
-        Tracing.deleteLogFiles()
+        Tracing.deleteLogFiles(in: Tracing.logsDirectory)
     }
     
     func testLogging() async throws {