update to go 1.16 and modules

asapo_tools/CMakeLists.txt

asapo_tools/src/asapo_tools/asapo

asapo_tools/src/asapo_tools/go.mod

asapo_tools/src/asapo_tools/go.sum

authorizer/CMakeLists.txt

authorizer/src/asapo_authorizer/go.mod

authorizer/src/asapo_authorizer/go.sum

broker/CMakeLists.txt

broker/src/asapo_broker/asapo-broker

broker/src/asapo_broker/database/mongodb_query.go

broker/src/asapo_broker/database/mongodb_test.go

broker/src/asapo_broker/go.mod

broker/src/asapo_broker/go.sum

discovery/src/asapo_discovery/go.mod

file_transfer/CMakeLists.txt

file_transfer/src/asapo_file_transfer/asapo-file-transfer

file_transfer/src/asapo_file_transfer/go.mod

file_transfer/src/asapo_file_transfer/go.sum