Arista: fix float in lexer

[dhalperi]

And add test for BGP ASN

[batfish-bot]

This change is 

[progwriter]

Reviewed 4 of 4 files at r1.
Reviewable status: complete! all files reviewed, all discussions resolved

[codecov]

Codecov Report

Merging #6058 into master will decrease coverage by 0.00%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #6058      +/-   ##
============================================
- Coverage     72.51%   72.51%   -0.01%     
+ Complexity    34574    34568       -6     
============================================
  Files          2816     2816              
  Lines        141407   141407              
  Branches      16989    16989              
============================================
- Hits         102548   102537      -11     
- Misses        30946    30955       +9     
- Partials       7913     7915       +2     

Impacted Files	Coverage Δ	Complexity Δ
.../src/main/java/org/batfish/datamodel/flow/Hop.java	53.33% <0.00%> (-6.67%)	5.00% <0.00%> (-1.00%)
.../org/batfish/dataplane/rib/RouteAdvertisement.java	84.78% <0.00%> (-4.35%)	16.00% <0.00%> (-1.00%)
...c/main/java/org/batfish/dataplane/rib/RibTree.java	89.58% <0.00%> (-4.17%)	27.00% <0.00%> (-1.00%)
...col/src/main/java/org/batfish/role/InferRoles.java	89.54% <0.00%> (-1.37%)	50.00% <0.00%> (-1.00%)
...a/org/batfish/representation/aws/LoadBalancer.java	82.18% <0.00%> (-0.32%)	70.00% <0.00%> (-1.00%)
...java/org/batfish/dataplane/ibdp/VirtualRouter.java	87.78% <0.00%> (-0.22%)	263.00% <0.00%> (-1.00%)