reject unsupported tuple components

[nerzh]

I noticed that jextract allowed multielement swift tuples in places where the JNI bridge later requires a concrete JavaBoxable type. Swift tuples cannot conform to protocols, so the generated code could fail to compile. I fixed it by rejecting unsupported tuple components during translation 🫣

ObertonWalletCore/destination/JExtractSwiftPlugin/Sources/BindingStore+SwiftJava.swift:24:41: error: type 'BindingStore.RawResponse' (aka '(requestId: UInt32, stringResponse: String, responseType: TSDKBindingResponseType, finished: Bool)') cannot conform to 'JavaBoxable' [#ProtocolTypeNonConformance]
22 | @_cdecl("Java_com_custwallet_core_BindingStore__00024getCompleteResponses__")
23 | public func Java_com_custwallet_core_BindingStore__00024getCompleteResponses__(environment: UnsafeMutablePointer<JNIEnv?>!, thisClass: jclass) -> jlong {
24 |   return BindingStore.completeResponses.dictionaryGetJNIValue(in: environment)
   |                                         |- error: type 'BindingStore.RawResponse' (aka '(requestId: UInt32, stringResponse: String, responseType: TSDKBindingResponseType, finished: Bool)') cannot conform to 'JavaBoxable' [#ProtocolTypeNonConformance]
   |                                         `- note: only concrete types such as structs, enums and classes can conform to protocols
25 | } // printCDecl(_:javaMethodName:parentName:parameters:resultType:_:) @ JExtractSwiftLib/JNISwift2JavaGenerator+SwiftThunkPrinting.swift:751
26 | 

/oberton-wallet-core/.build/checkouts/swift-java/Sources/SwiftJava/BridgedValues/JavaValue+Dictionary.swift:20:1: note: required by referencing instance method 'dictionaryGetJNIValue(in:)' on 'Dictionary' where 'Value' = 'BindingStore.RawResponse' (aka '(requestId: UInt32, stringResponse: String, responseType: TSDKBindingResponseType, finished: Bool)')
18 | // MARK: Dictionary extension for JNI bridging
19 | 
20 | extension Dictionary where Key: JavaBoxable & Hashable, Value: JavaBoxable {
   | `- note: required by referencing instance method 'dictionaryGetJNIValue(in:)' on 'Dictionary' where 'Value' = 'BindingStore.RawResponse' (aka '(requestId: UInt32, stringResponse: String, responseType: TSDKBindingResponseType, finished: Bool)')
21 |   /// Box this dictionary and return a jlong pointer for passing across JNI.
22 |   /// The dictionary is retained on the Swift heap; Java holds the pointer.