BGP: handle implicit confederation membership

[sfraint]

Handle case where one BGP peer is implicitly in a confederation with its peer.

[batfish-bot]

This change is 

[codecov]

Codecov Report

Merging #4990 into master will increase coverage by <.01%.
The diff coverage is 91.66%.

@@             Coverage Diff              @@
##             master    #4990      +/-   ##
============================================
+ Coverage     76.63%   76.63%   +<.01%     
- Complexity    29971    29972       +1     
============================================
  Files          2393     2393              
  Lines        115500   115510      +10     
  Branches      13645    13651       +6     
============================================
+ Hits          88508    88517       +9     
- Misses        20287    20288       +1     
  Partials       6705     6705

Impacted Files	Coverage Δ	Complexity Δ
...va/org/batfish/datamodel/bgp/BgpTopologyUtils.java	79.16% <91.66%> (+0.9%)	75 <0> (+6)	⬆️
.../src/main/java/org/batfish/datamodel/flow/Hop.java	53.33% <0%> (-6.67%)	5% <0%> (-1%)
...org/batfish/datamodel/flow/BidirectionalTrace.java	79.54% <0%> (-4.55%)	13% <0%> (-2%)
...java/org/batfish/symbolic/state/EdgeStateExpr.java	73.91% <0%> (-4.35%)	10% <0%> (-1%)
...tfish/representation/cisco/CiscoConfiguration.java	84.11% <0%> (+0.12%)	510% <0%> (+1%)	⬆️

[progwriter]

+reviewer:@corinaminer -reviewer:@progwriter

Reviewable status: 0 of 2 files reviewed, all discussions resolved (waiting on @corinaminer)

[corinaminer]

Reviewed 1 of 2 files at r1, 1 of 1 files at r2.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @sfraint)

---

projects/batfish-common-protocol/src/test/java/org/batfish/datamodel/bgp/BgpTopologyUtilsTest.java, line 407 at r2 (raw file):

    // Initiator implicitly matches listener confed, but remote ASNs doesn't overlap local AS
    assertPair(1L, null, LongSpace.of(2L), 1L, 3L, LongSpace.of(1L), null);
    assertPair(1L, null, LongSpace.of(1L), 1L, 3L, LongSpace.of(2L), null);

Only need half of these tests because assertPair tests both ways (swaps initiator and listener).

[dhalperi]

Reviewed 1 of 1 files at r3.
Reviewable status: complete! all files reviewed, all discussions resolved