Basic package setup (#1)

This PR contains the work done to setup this Swift package, so development can start from here.

Reviewed-on: rock-n-code/amiibo-api#1
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Tests/amiibo_apiTests.swift

@@ -1,5 +1,6 @@
 import Testing
-@testable import amiibo_api
+
+@testable import AmiiboAPI
 
 @Test func example() async throws {
     // Write your test here and use APIs like `#expect(...)` to check expected conditions.