Add list of supported types of mechanisms to NetworkServiceEndpoint entry

[denis-tingaikin]

Description

We can add the SupportedMechanisms field into NetworkServiceEndpoint to directly indicate what kinds of mechanisms the Endpoint could handle.

SupportedMechanisms is a list of Mechanisms kind, such as 'MEMIF', 'KERNEL', and so on.

Motivation

This can reduce the count of NSMgr tries on selecting cross-nse or nse. It can make Request for the Connection much faster on load. (NSMgr could just filter all NSEs from the registry before do Request to the next point)

Closes networkservicemesh/sdk#802

[denis-tingaikin]

The main questions are:

1. Can we face side effects?
2. What should we do on registering NSE which have not SupportedMechanisms?

[edwarnicke]

3. Does this potentially have application to the point to multipoint discussion?

[denis-tingaikin]

2. What should we do on registering NSE which have not SupportedMechanisms?

For this case, we could just reject the incoming request on the registry side.

1. Can we face side effects?

Currently, I see only fields that can be improved. I.e. no more permutation on selecting NSE/cross-NSE and also this should reduce requests count to the registry from nsmgr. Also, third-party apps that using the registry API could fast find NSEs that support specific mechanisms.

[denis-tingaikin]

/cc @fkautz

[denis-tingaikin]

@edwarnicke Do we have any updates on this?

[edwarnicke]

@denis-tingaikin Not yet... but I'll leave it in my notifications so I make sure to circle back to it.