clang-tidy: RpcClient.cpp - several errors regarding the callable type

[billpittman]

Showing all the errors that clang-tidy reported:
/data/ultifi/up-cpp/src/communication/RpcClient.cpp:135:18: error: 'callable' in capture list does not name a variable [clang-diagnostic-error]
/data/ultifi/up-cpp/src/communication/RpcClient.cpp:140:38: error: 'callable' in capture list does not name a variable [clang-diagnostic-error]
/data/ultifi/up-cpp/src/communication/RpcClient.cpp:142:6: error: reference to local binding 'callable' declared in enclosing function 'uprotocol::communication::RpcClient::invokeMethod' [clang-diagnostic-error]
/data/ultifi/up-cpp/src/communication/RpcClient.cpp:148:38: error: 'callable' in capture list does not name a variable [clang-diagnostic-error]
/data/ultifi/up-cpp/src/communication/RpcClient.cpp:150:6: error: reference to local binding 'callable' declared in enclosing function 'uprotocol::communication::RpcClient::invokeMethod' [clang-diagnostic-error]
/data/ultifi/up-cpp/src/communication/RpcClient.cpp:160:17: error: 'callable' in capture list does not name a variable [clang-diagnostic-error]
/data/ultifi/up-cpp/src/communication/RpcClient.cpp:162:25: error: 'callable' in capture list does not name a variable [clang-diagnostic-error]
/data/ultifi/up-cpp/src/communication/RpcClient.cpp:163:8: error: reference to local binding 'callable' declared in enclosing function 'uprotocol::communication::RpcClient::invokeMethod' [clang-diagnostic-error]

[gregmedd]

The clang compiler errors in #300 provide some clarity on the source of these issues. Using structured bindings in lambda captures is a C++20 feature. The pedantic compiler flags for gcc didn't catch that.

[PLeVasseur]

Confirmed this can be closed via #316