feat: add avoid missing enum constant in map rule

[incendial]

What is the purpose of this pull request? (put an "X" next to an item)

[ ] Documentation update
[ ] Bug fix
[X] New rule
[ ] Changes an existing rule
[ ] Add autofixing to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

[codecov]

Codecov Report

Merging #564 (e18dbeb) into master (e96739f) will increase coverage by 0.06%.
The diff coverage is 94.28%.

@@            Coverage Diff             @@
##           master     #564      +/-   ##
==========================================
+ Coverage   85.44%   85.51%   +0.06%     
==========================================
  Files         224      226       +2     
  Lines        4591     4626      +35     
==========================================
+ Hits         3923     3956      +33     
- Misses        668      670       +2     

Impacted Files	Coverage Δ
...c/analyzers/lint_analyzer/rules/rules_factory.dart	88.57% <0.00%> (-2.61%)	⬇️
...n_map/avoid_missing_enum_constant_in_map_rule.dart	100.00% <100.00%> (ø)
...st/avoid_missing_enum_constant_in_map/visitor.dart	100.00% <100.00%> (ø)

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