net: SvrError::ConnectionTimeout -> AllConnectionAttemptsFailed

The same error is being used both for timeouts and for "all attempts
failed"; if we're going to coalesce them (reasonable, given that the
only option in either case is "retry" or "don't"), "all attempts
failed" is a less misleading choice.

This changes the particular enum case in Swift from connectionTimedOut
to connectionFailed. Java continues to use NetworkException and
TypeScript the IoError code.

node/ts/test/NetTest.ts

@@ -834,7 +834,11 @@ describe('cdsi lookup', () => {
           ErrorCode.IoError,
           'websocket error: channel was idle for too long',
         ],
-        ['ConnectionTimedOut', ErrorCode.IoError, 'connect attempt timed out'],
+        [
+          'AllConnectionAttemptsFailed',
+          ErrorCode.IoError,
+          'no connection attempts succeeded before timeout',
+        ],
         ['ServerCrashed', ErrorCode.IoError, 'server error: crashed'],
       ];
       cases.forEach((testCase) => {