BridgeJS: Fix Array<@JSClass struct> support on imported interfaces

[kateinoigakukun]

Close #543

[Amzd]

enums as spit out by the playground do not compile on this branch

export type Foo = "a" | "b"
export function foo(): Foo

generates:

@JSFunction func foo() throws(JSException) -> Foo

enum Foo: String {
    case a = "a"
    case b = "b"
}
extension Foo: _BridgedSwiftEnumNoPayload, _BridgedSwiftRawValueEnum {}

error: Type 'Foo' does not conform to protocol '_BridgedSwiftStackType'

[Amzd]

nevermind, fixed with @_spi(BridgeJS) import JavaScriptKit