Fix Java map code generation

[Aayush10016]

Summary

Fixes generated Java for Concerto map declarations that use scalar aliases or imported map member types.

The Java visitor now:

• emits Map<K, V> consistently for map fields, getters, and setters
• unwraps scalar aliases used as map keys or values, for example SSN -> String
• avoids importing scalar and map declarations that are not emitted as Java classes
• imports non-scalar map member types, such as enums, when they are required by generated map fields
• enables the hr_integration Java compile verification case that was previously skipped for this bug

Validation

• npm.cmd ci
• npm.cmd run mocha -- test/codegen/fromcto/java/javavisitor.js
• npm.cmd run test:verify -- --grep "generated Java"
• npm.cmd run mocha -- test/codegen/codegen.js
• npm.cmd run test:verify
• npm.cmd run lint

npm.cmd test -- --grep JavaVisitor was also attempted, but the repository's global coverage gate still runs for filtered tests, so the focused mocha command above is the valid JavaVisitor test signal.

Fixes #265.