[Storage] Add method for creating multiple signed urls

[grdsdev]

Feature request

Add func createSignedURLs(paths: [String], expiresIn: Int, download: String? = nil) async throws -> [URL] method.

https://github.com/supabase/storage-js/blob/fa44be8156295ba6320ffeff96bdf91016536a46/src/packages/StorageFileApi.ts#L417