BgpProcess: only sort maps for JSON APIs

[dhalperi]

And make them immutable at conversion time to save space.

[batfish-bot]

This change is 

[codecov]

Codecov Report

Merging #8907 (d3f63d0) into master (90aacc8) will decrease coverage by 0.02%.
Report is 2 commits behind head on master.
The diff coverage is 100.00%.

❗ Current head d3f63d0 differs from pull request most recent head d61f6e8. Consider uploading reports for the commit d61f6e8 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8907      +/-   ##
==========================================
- Coverage   72.51%   72.50%   -0.02%     
==========================================
  Files        3319     3319              
  Lines      169420   169432      +12     
  Branches    19878    19880       +2     
==========================================
- Hits       122854   122845       -9     
- Misses      37420    37437      +17     
- Partials     9146     9150       +4     

Files	Coverage Δ
...rc/main/java/org/batfish/datamodel/BgpProcess.java	83.60% <100.00%> (+0.27%)	⬆️
.../org/batfish/dataplane/ibdp/BgpRoutingProcess.java	84.66% <100.00%> (ø)
...java/org/batfish/dataplane/ibdp/VirtualRouter.java	88.23% <100.00%> (-0.26%)	⬇️
...rc/main/java/org/batfish/dataplane/rib/BgpRib.java	90.04% <100.00%> (+0.04%)	⬆️
.../java/org/batfish/job/ConvertConfigurationJob.java	88.19% <100.00%> (+0.16%)	⬆️

... and 5 files with indirect coverage changes

[SLarkworthy]

Reviewable status: 0 of 5 files reviewed, all discussions resolved

[SLarkworthy]

Reviewed 5 of 5 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @dhalperi)