Update GoogleSignIn to 6.0.1

[dvdchr]

Closes #609

This updates GoogleSignIn to version 6.0.1, enabling support for M1. Some adjustments were required due to breaking changes introduced in version 6.0.0. Google has conveniently provided a migration checklist:

• Update all [GIDSignIn sharedInstance] (or GIDSignIn.sharedInstance()) calls to GIDSignIn.sharedInstance property accesses.

• Move all client configuration (client IDs, etc.) to a GIDConfiguration object.

• Update calls to removed methods to their new equivalents:

  v5.x.x	v6.0.0	Status
  signIn	signInWithConfiguration:presentingViewController:callback:	✅ Done. Previous signIn method in GIDSignInDelegate extension is migrated.
  restorePreviousSignIn	restorePreviousSignInWithCallback:	✅ Done. Method is not used.
  disconnect	disconnectWithCallBack:	✅ Done. Previous disconnect method in GIDSignInDelegate is not implemented, so there's no need to define the callback.
  getTokensWithHandler:	doWithFreshTokens:	✅ Done. Method is not used.
  refreshTokensWithHandler:	doWithFreshTokens	✅ Done. Method is not used.

• Remove all references to the GIDSignInDelegate protocol and its methods.

  • Move the logic from signIn:didSignInForUser:withError: to the callback block of signInWithConfiguration:presentingViewController:callback:.
  • Move the logic from signIn:didDisconnectWithUser:withError: to the callback block of disconnectWithCallback:.

• Manually connect GIDSignInButton to a method that calls signInWithConfiguration:presentingViewController:callback: using an IBAction or similar.

Todos:

• Ensure that this change does not affect the authentication flow in WordPress.
• Ensure that this change does not affect the authentication flow in WooCommerce.
• Bump podspec version to 1.41.0-beta.2

[ealeksandrov]

Thank you for this update!
Code changes: ✅
Nit: don't forget to add 1.41.0-beta.2 tag on latest commit here, so we won't need to specify branch name in client Podfiles (which also will break after a merge and branch deletion here).

I've tested it on:

• WC-iOS (woocommerce/woocommerce-ios#4725)
  • with fresh Google email, linking it to WP account in process
  • logged out and back in with same email
• WP-iOS (wordpress-mobile/WordPress-iOS#16974)
  • logged in with Google account linked above, logging out
  • disconnected Google on WP.com
  • connected Google account with same WP account back in WP-iOS login flow

All tested on M1, but with Xcode in Rosetta mode.

LGTM!

[dvdchr]

Thanks @ealeksandrov! I've tagged the merge commit and published a pre-release for version 1.41.0-beta.2. 🙂