Add <gtest/gtest.h> include to tests

test/test_ccaosdb.cpp

test/test_configuration.cpp

test/test_connection.cpp

test/test_data_type.cpp

test/test_entity.cpp

test/test_file_transmission.cpp

test/test_info.cpp

test/test_issues.cpp

test/test_list_properties.cpp

test/test_protobuf.cpp

test/test_transaction.cpp

test/test_user.cpp

test/test_utility.cpp

test/test_value.cpp