add vfconfig client chain element

[pperiyasamy]

this enables facility to store vfinfo (pf, vf interface names, vf num) in resource pool client chain element and this info would get referred in further chain elements.

Signed-off-by: Periyasamy Palanisamy periyasamy.palanisamy@est.tech

[Bolodya1997]

vfconfig server injects VF config into the Request context, so it is accessible both from the server and from the client chain elements. If you want to create different VF configs for the server chain before connect and for the client chain in the connect, you probably need to add some isClient flag as it is done in metadata:
https://github.com/networkservicemesh/sdk/blob/fe8d8e6e825a3ff8024b8f8726eb028e2385ca1f/pkg/networkservice/utils/metadata/context.go#L49
In such case there is no need to add vfconfig client, you more probably just need to alter vfconfig context methods in the sdk-kernel:
https://github.com/networkservicemesh/sdk-kernel/blob/main/pkg/kernel/networkservice/vfconfig/context.go

So for me this client looks applicable only for the pure client chains (only on NSC), so if you are not planning to use it in there, I don't think that we need these changes.

[pperiyasamy]

@Bolodya1997 yes, you are correct, both client and server going to consume different vfconfig, so this must be enhanced to have isClient flag to have both server and client vfconfig. I think you meant to change vfconfig/context.go with APIs to something similar to this. Am I correct ?

[pperiyasamy]

This need rebase after this sdk-kernel PR is merged and CI is expected to pass.

[denis-tingaikin]

@pperiyasamy Could you rebase this PR?

[denis-tingaikin]

@Bolodya1997 Could you also review this?