Index TypeUtils schema name lookups

[iuliiasobolevska]

Summary

Replace the remaining per-field schema scans in Java TypeUtils with lookups against the document-scoped SchemaIndex.

The indexed lookups cover:

• object and interface detection for wildcard list return types
• enum, union, and interface detection when generating interface return types
• object and enum detection when schema definitions shadow built-in common scalar mappings

The public TypeUtils constructor that accepts a Document remains unchanged.

Relationship to #962

#962 introduced SchemaIndex, built its document-order-preserving definitionsByName map once, and shared that index through the generator graph.
Its PR description explicitly left the residual per-field scans in TypeUtils for a separate optimization.

This PR is that follow-up.
It preserves #962's definitionsByName implementation and adds type-kind predicates that inspect only definitions(name), reusing the existing map instead of scanning every document definition or building a competing index.

Performance

The real ot-occommon-dgs consumer benchmark at commit 8ce1311d generated 9,015 files and measured:

Revision	Median	Range
Current master (7100dae0)	2.33 s	2.29–2.59 s
This PR	2.236 s	2.180–2.313 s

The nominal median improvement is 4.0%.
Because the ranges overlap, this is directional evidence rather than a claim of a stable 4% speedup.

Every run produced the same 41,058,296 bytes across the same 9,015 paths with complete-tree SHA-256 cb765785686ac0f9d6c709cbc00ab3d635899e5932e5db361cd56fbc195132f3.

Correctness safeguards

• Preserve wildcard resolution when schemas contain both Foo and IFoo.
• Preserve interface, enum, and union return-type behavior.
• Preserve schema-defined Date and PageInfo shadowing of built-in mappings.
• Preserve Index schema model lookups during code generation #962's same-name and document-order lookup semantics.

Verification

• ./gradlew :graphql-dgs-codegen-core:test :graphql-dgs-codegen-core:integTest :graphql-dgs-codegen-core:lintKotlinMain :graphql-dgs-codegen-core:lintKotlinTest --no-scan
• Real-consumer benchmark with byte-identical generated output