epic: create a roadmap with future use cases to be supported by Kytos

[italovalcy]

As we discussed on the Kytos meeting, this issue aims to document the future use cases to be supported by Kytos

[jab1982]

List to start with:

L2VPN: P2P and P2MP
Sub-second Service Protection (static and dynamic)
Service/Traffic Prioritization
Per-Port and Per-VLAN Port Looping
Port Mirroring
Flow Mirroring
Telemetry (INT and counters/statistics)
Contention
In-line Traffic steering
Frame Sequence Tracking
Web User Interface, CLI, and API
Pathfinder with support for asset_group (a bunch of services that seem to be independent but they share the underlay)

[jab1982]

Port Loop must be allowed in any interface, including NNI, but it should only impact user flows, not topology discovery or continuity checks.