Use getAuthIdentifier() instead of getKey() to retrieve current user identifier

[s207152]

In core framework, getAuthIdentifier() is used to get user identifier for authentication.
However, in passport getKey() is used to get user identifier.

Below are the places where made us confused:

passport/src/Http/Controllers/AuthorizedAccessTokenController.php

Lines 35 to 42 in 4e3390e

	public function forUser(Request $request)
	{
	$tokens = $this->tokenRepository->forUser($request->user()->getKey());
	return $tokens->load('client')->filter(function ($token) {
	return ! $token->client->firstParty() && ! $token->revoked;
	})->values();
	}

passport/src/Http/Controllers/AuthorizationController.php

Lines 107 to 116 in 55c1c54

	protected function approveRequest($authRequest, $user)
	{
	$authRequest->setUser(new User($user->getKey()));
	$authRequest->setAuthorizationApproved(true);
	return $this->convertResponse(
	$this->server->completeAuthorizationRequest($authRequest, new Psr7Response)
	);
	}

In our case, we used uuid as auth identifier but kept primary key as $primaryKey field for relationships.

Would you consider to change to use getAuthIdentifier() to be in sync with core framework design?

[driesvints]

Hmm yes I believe so but we'd have to make the change on the next major release.