FRR: Parse IPv6 BGP neighbors

[ratulm]

Fixes #6586

[batfish-bot]

This change is 

[codecov]

Codecov Report

Merging #6587 (0f169cd) into master (b7639c5) will decrease coverage by 0.01%.
The diff coverage is 83.33%.

@@             Coverage Diff              @@
##             master    #6587      +/-   ##
============================================
- Coverage     73.39%   73.38%   -0.02%     
+ Complexity    35768    35762       -6     
============================================
  Files          2838     2839       +1     
  Lines        144381   144390       +9     
  Branches      17475    17475              
============================================
- Hits         105971   105958      -13     
- Misses        30004    30020      +16     
- Partials       8406     8412       +6     

Impacted Files	Coverage Δ	Complexity Δ
...ish/representation/cumulus/CumulusConversions.java	91.77% <0.00%> (ø)	191.00 <0.00> (ø)
...atfish/representation/cumulus/BgpIpv6Neighbor.java	75.00% <75.00%> (ø)	1.00 <1.00> (?)
...ar/cumulus_frr/CumulusFrrConfigurationBuilder.java	75.19% <100.00%> (+0.19%)	170.00 <3.00> (+2.00)
...rg/batfish/identifiers/StorageBasedIdResolver.java	85.29% <0.00%> (-5.89%)	22.00% <0.00%> (ø%)
.../org/batfish/dataplane/rib/RouteAdvertisement.java	83.67% <0.00%> (-4.09%)	18.00% <0.00%> (-1.00%)
...org/batfish/datamodel/flow/BidirectionalTrace.java	81.81% <0.00%> (-2.28%)	14.00% <0.00%> (-1.00%)
...src/main/java/org/batfish/coordinator/PoolMgr.java	59.52% <0.00%> (-1.20%)	15.00% <0.00%> (-1.00%)
...ain/java/org/batfish/storage/FileBasedStorage.java	86.19% <0.00%> (-0.68%)	249.00% <0.00%> (ø%)
...java/org/batfish/dataplane/ibdp/VirtualRouter.java	90.45% <0.00%> (-0.32%)	206.00% <0.00%> (-1.00%)
...a/org/batfish/representation/aws/LoadBalancer.java	82.18% <0.00%> (-0.32%)	70.00% <0.00%> (-1.00%)
... and 3 more

[dhalperi]

Reviewed 6 of 6 files at r1.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @arifogel and @ratulm)

---

projects/batfish/src/main/antlr4/org/batfish/grammar/cumulus_frr/CumulusFrr_bgp.g4, line 211 at r1 (raw file):

  (
     ip = IP_ADDRESS
     | ip6 = IPV6_ADDRESS

probably worth factoring out into sbn_ip6 instead of combining here.

[ratulm]

The last commit (0f169cd) adds parsing for some more IPv6 related stuff to make the user file behave alright.

[dhalperi]

Reviewed 6 of 6 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @arifogel)