fix: drop unmappable types in nested and union schemas

[alleknalle]

swagger-php only dropped types with no OpenAPI representation (callable, resource, ...) at the top level, so nested and union positions emitted an invalid type (e.g. items: {type: callable}). Drop them in setSchemaType, leaving the schema open instead.

Summary

swagger-php only applies its "drop unmappable type" sanity check to the top-level schema, so nested and union positions leak the raw PHP type name and emit invalid output:

Input	Before	After
list<callable>	items: {type: callable}	items: {}
array<string, callable>	additionalProperties: {type: callable}	additionalProperties: {}
int|callable	type: [callable, integer]	type: [integer]

The fix drops these in setSchemaType, where the type is known to be a BuiltinType (callable, resource, iterable, …) rather than a class — so object/class types still resolve to $refs as before. mapNativeType id: it must keep passing class-name strings through for later $ref resolution.

Out of scope: the rare non-all-builtin union where the builtin member itself is unmappable (e.g. Foo|callable); happy to extend if wanted.

Type of Change

• Bug fix (non-breaking change that fixes an issue)

Related Issues

None.

Test Plan

Resolver-level cases in tests/Type/TypeResolverTest (list<callable>, array<string, callable>) and an end-to-end case in tests/Processors/AugmentPropertiesTest(via theAugmentPropertiesprocessor).composer test+composer analyse` green.

• Unit tests added/updated
• Integration tests added/updated

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code where necessary
• I have updated the documentation accordingly
• My changes generate no new warnings
• New and existing tests pass locally
• Any dependent changes have been merged and published

[DerManoMann]

could this comment be moved (and adjusted) to the method docblock in stead, please?
Checks that the given type ...