Fix base migration to check if table already exists

Currently the base schema migration assumes that the "elastic_migrations" table does not exist.

This is problematic when restoring a schema from a schema:dump with prune: `php artisan schema:dump --prune`

When you run `php artisan migrate`, Laravel restores the schema dump in database/schema. However, if you then try to run a migration, the elastic-migrations library attempts to run its migrations, but throws an error because the table already exists via the schema being restored.

`SQLSTATE[42P07]: Duplicate table: 7 ERROR:  relation "elastic_migrations" already exists (SQL: create table "elastic_migrations" ("migration" varchar(255) not null, "batch" integer not null))`

database/migrations/2019_15_12_112000_create_elastic_migrations_table.php

@@ -15,10 +15,12 @@ public function __construct()
 
     public function up(): void
     {
-        Schema::create($this->table, static function (Blueprint $table) {
-            $table->string('migration')->primary();
-            $table->integer('batch');
-        });
+        if (!Schema::hasTable($this->table)) {
+            Schema::create($this->table, static function (Blueprint $table) {
+                $table->string('migration')->primary();
+                $table->integer('batch');
+            });
+        }
     }
 
     public function down(): void