Add unit tests for JsonPrettifier, graphql.Utils, and GraphQLSchemaTo…

[abdulhasyyb]

…SDL (#193)

Summary

Addresses #193 by adding initial unit test infrastructure and coverage to InQL.

The project currently has no src/test directory or test framework configured, so this PR sets up JUnit 5 (useJUnitPlatform()) and adds test coverage as a starting point.

What's covered

• JsonPrettifier — valid JSON formatting, nested structures, arrays, non-HTML-escaping, malformed-input fallback behavior, and primitive values
• inql.graphql.Utils — formatComment (List overload, including line-wrapping), unwrapType, isBuiltInScalarType
• GraphQLSchemaToSDL — round-trips a schema built via graphql-java's own SchemaParser/SchemaGenerator through schemaToSDL(), covering object types, custom scalars, enums, and interfaces

Scope notes

This is intentionally scoped to classes that don't touch Burp's Montoya API (HttpRequest, UI components, etc.), since those need mocking/fixture work that felt like a separate, larger PR. Happy to follow up with:

• getGraphQLOperations / other request-parsing functions in graphql.Utils (needs HttpRequest test doubles)
• GQLQueryPrinter (query generation from schema — core to InQL's scanning feature)

if this approach looks right to you.

Testing

./gradlew test and ./gradlew build both pass locally against dev (JDK 17).