Remove map structs

[tsmbland]

Description

Turning existing map structs into type aliases. Removes a lot of code, with only minor refactoring required

Fixes # (issue)

Type of change

• Bug fix (non-breaking change to fix an issue)
• New feature (non-breaking change to add functionality)
• Refactoring (non-breaking, non-functional change to improve maintainability)
• Optimization (non-breaking change to speed up the code)
• Breaking change (whatever its nature)
• Documentation (improve or add documentation)

Key checklist

• All tests pass: $ cargo test
• The documentation builds and looks OK: $ cargo doc

Further checks

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.03%. Comparing base (28972b7) to head (f76027b).
Report is 11 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #490      +/-   ##
==========================================
- Coverage   95.03%   95.03%   -0.01%     
==========================================
  Files          36       36              
  Lines        4914     4893      -21     
  Branches     4914     4893      -21     
==========================================
- Hits         4670     4650      -20     
  Misses        123      123              
+ Partials      121      120       -1     

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[alexdewar]

I think I prefer this to #489 (although that is ok as a solution too). It's just a bit simpler. The only downside is that some things look a bit uglier with extra &s and clone()s, but I'm not sure it's worth having custom structs just to avoid that.

[tsmbland]

Ok thanks, I'll go ahead with this approach then, and give it a go for the remaining maps still left to implement. Can always switch back to custom structs later if we feel it's necessary, but I doubt it