Support version 0.4 of SMIRNOFF Electrostatics section

[mattwthompson]

Resolves #1084 in part

Fixes #1288

• Blocked by OFF-EP 0005b standards#34
• Add up-converters
• Test up-converters
• Handle switch_width in electrostatics handler Do not handle, but explicitly do not handle
• Band-aid old code paths?
• Update Interchange - I'd like to do this after this PR to avoid too many feature branches being split off
• Tag issue being addressed
• Add tests
• Update docstrings/documentation, if applicable - I did a scan for .method and similar patterns and didn't find anything obviously outdated.
• Lint codebase
• Update changelog

[codecov]

Codecov Report

Merging #1277 (1d7e1d7) into topology-biopolymer-refactor (8128d0b) will decrease coverage by 2.54%.
The diff coverage is 96.05%.

[j-wags]

Ok, I hammered on this a bit and it looks like everything works well. The only thing this PR still needs to add the solvent_dielectric ParameterAttribute required in the 0.4 Electrostatics spec. Per the spec, it should default to "none", and it's fine if we have the setter just raise a NotImplementedError if someone tries to set it to anything else.

Also (per inline comment) I don't think we should even try to support unexpected 0.3 methods - It would be fine if anything fishy just raises an error.

[j-wags]

Nice - Thanks @mattwthompson! Feel free to merge once tests pass.