Replace BGP RR/NHS logic with neighbor attributes #2251
Description
Instead of the current logic which goes along the lines of: is it an IBGP neighbor, and am I a RR, and is he not a RR... we should have per-neighbor rr_client (true) and next_hop_self (true/all) attributes that would be computed in the BGP module.
These attributes would then be used to in BGP templates to set neighbor options.
The logic should be backward-compatible (apart from EOS/FRR/IOS where it would also replace the fixed IBGP local-as settings), so the change wouldn't force us to redo/retest all templates, but I definitely hope we'll find it convenient to remove the old mess (OK, maybe not from the SONiC/IOS XR/RouterOS templates 😜)