Cumulus: convert L2 and L3 VNIs to separate structures

[progwriter]

In line with what we do for other vendors (NXOS and Arista)

[batfish-bot]

This change is 

[codecov]

Codecov Report

Merging #5262 into master will decrease coverage by <.01%.
The diff coverage is 95%.

@@             Coverage Diff              @@
##             master    #5262      +/-   ##
============================================
- Coverage     73.37%   73.36%   -0.01%     
+ Complexity    31903    31900       -3     
============================================
  Files          2619     2619              
  Lines        128676   128699      +23     
  Branches      15456    15458       +2     
============================================
+ Hits          94415    94425      +10     
- Misses        26803    26811       +8     
- Partials       7458     7463       +5

Impacted Files	Coverage Δ	Complexity Δ
...presentation/cumulus/CumulusNcluConfiguration.java	92.81% <95%> (-0.04%)	230 <4> (+4)
...n/java/org/batfish/datamodel/acl/AclLineIndex.java	33.33% <0%> (-5.56%)	4% <0%> (-1%)
...c/main/java/org/batfish/dataplane/rib/RibTree.java	89.58% <0%> (-4.17%)	27% <0%> (-1%)
...ain/java/org/batfish/symbolic/IngressLocation.java	65.78% <0%> (-2.64%)	15% <0%> (-1%)
...org/batfish/datamodel/flow/BidirectionalTrace.java	81.81% <0%> (-2.28%)	14% <0%> (-1%)
...col/src/main/java/org/batfish/role/InferRoles.java	89.54% <0%> (-1.37%)	50% <0%> (-1%)
...java/org/batfish/dataplane/ibdp/VirtualRouter.java	87.91% <0%> (-0.32%)	261% <0%> (-2%)
...batfish/src/main/java/org/batfish/main/Driver.java	38.25% <0%> (-0.25%)	28% <0%> (ø)
...src/main/java/org/batfish/coordinator/PoolMgr.java	65.16% <0%> (+1.12%)	16% <0%> (+1%)	⬆️

[dhalperi]

Reviewed 2 of 2 files at r1.
Reviewable status: complete! all files reviewed, all discussions resolved