Rework tunnels to support statistics

cmd/rdpgw/common/remote.go

cmd/rdpgw/main.go

cmd/rdpgw/protocol/client.go

cmd/rdpgw/protocol/common.go

cmd/rdpgw/protocol/gateway.go

cmd/rdpgw/protocol/process.go

cmd/rdpgw/protocol/track.go

cmd/rdpgw/protocol/tunnel.go

cmd/rdpgw/security/basic.go

cmd/rdpgw/security/basic_test.go

cmd/rdpgw/security/jwt.go

cmd/rdpgw/web/basic.go

cmd/rdpgw/web/oidc.go

go.mod