refactor: Clean up Foxglove Websocket Server

This uses the Base64Encode function from the foxglove repository. It should be functionally the same. The only difference is that the function in the foxglove header is non-static accepts a const std::string_view&, while here it is static and accepts a std::string_view.

Also, the definition for foxglove::Server<WebSocketNoTls>::setupTlsHandler() is removed.