Add support for jobs & queueables, migrations

- Create migration directives & migrators
- Modify Cache classes to support array manipulation
- Create Redis unit and RedisCache implementation
- Create Queueable base class and Queue class that uses Cache backend

src/orm/support/CacheModel.ts

@@ -1,6 +1,8 @@
 import {Model} from '../model/Model'
 import {Field} from '../model/Field'
 import {FieldType} from '../types'
+import {Maybe} from '../../util'
+import {ModelBuilder} from '../model/ModelBuilder'
 
 /**
  * A model instance which stores records from the ORMCache driver.
@@ -18,4 +20,15 @@ export class CacheModel extends Model<CacheModel> {
 
     @Field(FieldType.timestamp, 'cache_expires')
     public cacheExpires?: Date;
+
+    public static withCacheKey(key: string): ModelBuilder<CacheModel> {
+        return this.query<CacheModel>()
+            .whereKey(key)
+            .whereProperty('cacheExpires', '>', new Date())
+    }
+
+    public static getCacheKey(key: string): Promise<Maybe<CacheModel>> {
+        return this.withCacheKey(key)
+            .first()
+    }
 }