Implement OAuth and SAML2 support (#13764)

* Implement OAuth and SAML2 support via Socialite

* Add socialite docs

* fixes

* Additional information added

* wip

* 22.3.0 targeted version

* Allow mysql auth as long as there is a password saved

Co-authored-by: laf <gh+n@laf.io>
Co-authored-by: Tony Murray <murraytony@gmail.com>

database/migrations/2022_02_03_164059_increase_auth_id_length.php

@@ -0,0 +1,32 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+class IncreaseAuthIdLength extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        Schema::table('users', function (Blueprint $table) {
+            $table->string('auth_id')->nullable()->change();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down()
+    {
+        Schema::table('users', function (Blueprint $table) {
+            $table->integer('auth_id')->nullable()->change();
+        });
+    }
+}