Add GetFileTransferParams functor

Sources/ElixxirDAppsSDK/GetFileTransferParams.swift

+import Bindings
+import XCTestDynamicOverlay
+
+public struct GetFileTransferParams {
+  public var run: () -> Data
+
+  public func callAsFunction() -> Data {
+    run()
+  }
+}
+
+extension GetFileTransferParams {
+  public static let liveDefault = GetFileTransferParams {
+    guard let data = BindingsGetDefaultFileTransferParams() else {
+      fatalError("BindingsGetDefaultFileTransferParams returned `nil`")
+    }
+    return data
+  }
+}
+
+extension GetFileTransferParams {
+  public static let unimplemented = GetCmixParams(
+    run: XCTUnimplemented("\(Self.self)")
+  )
+}
+