CA warnings when building tests

found during #1565 (closed)

In file included from ca_cfg_mgr_unittests.cc:14:
../../../../src/bin/agent/tests/test_libraries.h:23:20: warning: ‘{anonymous}::BASIC_AUTH_LIBRARY’ defined but not used [-Wunused-variable]
   23 | static const char* BASIC_AUTH_LIBRARY = "/home/razvan/isc/releases/kea-1.9.2-rc1/kea-1.9.2-work/src/bin/agent/tests/.libs/libbasicauth.so";
      |                    ^~~~~~~~~~~~~~~~~~
In file included from ca_response_creator_unittests.cc:20:
../../../../src/bin/agent/tests/test_libraries.h:20:20: warning: ‘{anonymous}::CALLOUT_LIBRARY’ defined but not used [-Wunused-variable]
   20 | static const char* CALLOUT_LIBRARY = "/home/razvan/isc/releases/kea-1.9.2-rc1/kea-1.9.2-work/src/bin/agent/tests/.libs/libcallout.so";
      |                    ^~~~~~~~~~~~~~~
  CXX      ca_unittests-parser_unittests.o
  CXX      ca_unittests-get_config_unittest.o
  CXX      libcallout_la-callout_library.lo
  CXX      libbasicauth_la-basic_auth_library.lo
In file included from get_config_unittest.cc:24:
test_libraries.h:23:20: warning: ‘{anonymous}::BASIC_AUTH_LIBRARY’ defined but not used [-Wunused-variable]
   23 | static const char* BASIC_AUTH_LIBRARY = "/home/razvan/isc/releases/kea-1.9.2-rc1/kea-1.9.2-work/src/bin/agent/tests/.libs/libbasicauth.so";
      |                    ^~~~~~~~~~~~~~~~~~
basic_auth_library.cc: In member function ‘virtual isc::http::HttpResponsePtr {anonymous}::ResponseCreator::createStockHttpResponse(const HttpRequestPtr&, const isc::http::HttpStatusCode&) const’:
basic_auth_library.cc:63:64: warning: unused parameter ‘request’ [-Wunused-parameter]
   63 | ResponseCreator::createStockHttpResponse(const HttpRequestPtr& request,
      |                                          ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
basic_auth_library.cc: In member function ‘virtual isc::http::HttpResponsePtr {anonymous}::ResponseCreator::createDynamicHttpResponse(isc::http::HttpRequestPtr)’:
basic_auth_library.cc:72:59: warning: unused parameter ‘request’ [-Wunused-parameter]
   72 | ResponseCreator::createDynamicHttpResponse(HttpRequestPtr request) {