feat(map): Codegen for Avro IDL Target

[jonathan-casey]

Sample

   record Company {
      string name;
      Address headquarters;
      map<string> companyProperties;
      map<Employee> employeeDirectory;
      map<TShirtSizeType> employeeTShirtSizes;
      map<Concept> employeeProfiles;
      map<string> employeeSocialSecurityNumbers;
   }

Author Checklist

• Ensure you provide a DCO sign-off for your commits using the --signoff option of git commit.
• Vital features and changes captured in unit and/or integration tests
• Commits messages follow AP format
• Extend the documentation, if necessary
• Merging to main from fork:branchname

[coveralls]

coverage: 98.921% (+0.004%) from 98.917%
when pulling 31c487d on jonathan/codegen_map_avro
into e22a321 on main.