* Add TargetPort to RouteToApp and AppMetadata proto messages
* Pass TargetPort during cert generation
* Refactor Pack.makeTLSConfig to accept struct
This will make it easier to add targetPort to it.
* Add labels to UUIDs used by appaccess test pack app servers
This makes them easier to distinguish when routing doesn't work as expected.
* Refactor Pack.CreateAppSession to accept a struct
* TestTCP: Create app session within test
If we kept the old code, we'd need to manually create a session for each
target port, which would create a lot of duplication.
* Prepare integration test fixtures for multi-port tests
* Add api/utils/net.IsPortInRange
* Use TargetPort when routing TCP connections
* Inline dialMultiPortTCPApp, centralize logic
* Check target port when connecting to single-port app
* Reorder check in IsPortInRange
* Use int instead of uint16
* Extract picking dialTarget to separate function
* addr → uriAddr
* Improve err msg for single-port apps when targetPort != uriPort
* Fix unnecessary conversion to int
* Add Ports to AppSpecV3
* Validate ports of api/types.AppV3
* Add Ports to lib/config and lib/service/servicecfg
* lib/config TestApps: Improve error messages
* lib/service: Convert servicecfg.PortRange to types.PortRange
* Add multi-port TCP apps to config and tctl tests
* Rename Ports to TCPPorts
* Change port fields to uint16 where possible
* Update comments for Port and EndPort
* Extract port range validation to api/utils/net
* Replace custom check type with require.ErrorAssertionFunc
* Simplify validation of end port
* Fix expected message in api/types test
I forgot to update that one.
Rafał Cieślak