[ntcore] Various NT4 fixes (#4474)

* TopicListener: Fix Add() return values
* Update PubSubOption poll storage documentation
* Update NetworkTableEntry::GetValue() doc
* Add documentation regarding asynchronous callbacks
* Unpublish entry: set publisher to nullptr
* Implement ValueListenerPoller default constructor
* Remove SetNetworkIdentity, make parameter to StartClient
* URI-escape client ID, improve error message
* Add connected message with client id; also improve disconnected message a bit
* Handle SetServers either before or after StartClient
* Fix client use-after-free; also delay reconnect after disconnect to rate limit
* Don't re-announce to already subscribed client; we especially don't want to send the last value again
* Always accept in-order sets, only use timestamp for tiebreak
* Fix LocalStorage::StartNetwork race
* Remove unused/unimplemented function

Also:
* [glass] Remove debug print
* [glass] Fix mpack string decoding
* [cameraserver] Fix up startclient

ntcore/src/test/native/cpp/net/MockNetworkInterface.h

@@ -77,9 +77,9 @@ class MockLocalStorage : public ILocalStorage {
               (override));
   MOCK_METHOD(void, NetworkSetValue, (NT_Topic topicHandle, const Value& value),
               (override));
-  MOCK_METHOD(void, StartNetwork, (NetworkStartupInterface & startup),
+  MOCK_METHOD(void, StartNetwork,
+              (NetworkStartupInterface & startup, NetworkInterface* network),
               (override));
-  MOCK_METHOD(void, SetNetwork, (NetworkInterface * network), (override));
   MOCK_METHOD(void, ClearNetwork, (), (override));
 };