Closes #77.

Adds the ability to optionally pass a name when creating a match, matching the other Nakama SDKs. Per the documentation, the name is used by the server to generate the match ID, so two clients creating a match with the same name end up in the same match.

Implementation

• Added an optional name parameter to createMatch / createMatchAsync (and the NRtClientInterface declarations), using std::optional<std::string> to follow the existing listMatches convention.
• Used std::optional rather than a defaulted empty string so the no-name behaviour is preserved exactly, mutable_match_create() is always called, and set_name only runs when a name is actually provided. Existing callers are unaffected.

Note on the test

The test creates two matches with the same name from a single session and asserts they return the same match ID. If the server behaves differently for a same-session repeat, I'm happy to switch it to a two-session setup like test_rt_matchmaker

Testing

• Added test_rt_create_match_with_name in test_match.cpp, registered in test_rt_match(). It creates two matches with the same name and asserts they return the same match ID, verifying the name feeds into ID generation.
• Compiles cleanly on Windows (win-x64, MSVC).