wrap-java: Fix compilation errors for generic collections

[sidepelican]

This PR is part of the improvements for #599.

It resolves two specific types of compilation errors encountered during code generation.
Fixing these allows for the successful generation of JavaCollection, JavaSet, List and other similar types.

Error A: Metatype generic parameters

In Swift, generic type parameters cannot be used as macro arguments.
Following existing implementations, I'm using JavaObject as a placeholder in those contexts.

.../JavaSet.swift:4:42: error: type 'E' does not conform to protocol 'AnyJavaObject'
  2 | import SwiftJavaJNICore
  3 | 
  4 | @JavaInterface("java.util.Set", extends: JavaCollection<E>.self)
    |                                          `- error: type 'E' does not conform to protocol 'AnyJavaObject'
  5 | public struct JavaSet<E: AnyJavaObject> {
  6 |   /// Java method `remove`.

Error B: Generic parameters in Java arrays

The generic type parameters within Java array types (e.g., T[]) were not being correctly detected.

.../JavaSet.swift:76:41: error: cannot find type 'T' in scope
 74 |   /// ```
 75 |   @JavaMethod
 76 |   public func toArray(_ arg0: [T?]) -> [T?]
    |                                         `- error: cannot find type 'T' in scope
 77 | 
 78 |   /// Java method `toArray`.

[ktoso]

wohoo!

[ktoso]

Awesome as well :)