Add Migration Graph Builder

[acrutt]

Adding a new MapBuilder to create migration graphs from an InsertionElectrode collection. Based on MigrationGraphDoc developed by @hmlli in #437

[codecov-commenter]

Codecov Report

Merging #468 (98b71e6) into main (c01c332) will decrease coverage by 0.02%.
The diff coverage is 83.72%.

@@            Coverage Diff             @@
##             main     #468      +/-   ##
==========================================
- Coverage   97.61%   97.58%   -0.03%     
==========================================
  Files         115      116       +1     
  Lines       24011    24054      +43     
==========================================
+ Hits        23438    23474      +36     
- Misses        573      580       +7     

Impacted Files	Coverage Δ
emmet-core/emmet/core/mobility/migrationgraph.py	94.91% <ø> (ø)
...uilders/emmet/builders/mobility/migration_graph.py	83.72% <83.72%> (ø)

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[munrojm]

Thanks @acrutt and @hmlli !!

I remember @hmlli originally having a try-except block in a document construction method. If document construction failure is possible, but the desire is to exclude the failure and keep processing, then a try-except block should be added to the builder processing method.

[acrutt]

@munrojm I finished updating the builder after @hmlli latest changes to the MigrationGraphDoc. I think this is ready to merge unless you have any suggested edits!