feat(#31): implemented api for environment crud operations

backend/src/models/integration.ts

@@ -1,9 +1,5 @@
 import { Schema, model, Types } from 'mongoose';
 import {
-  ENV_DEV,
-  ENV_TESTING,
-  ENV_STAGING,
-  ENV_PROD,
   INTEGRATION_HEROKU,
   INTEGRATION_VERCEL,
   INTEGRATION_NETLIFY,
@@ -32,7 +28,6 @@ const integrationSchema = new Schema<IIntegration>(
     },
     environment: {
       type: String,
-      enum: [ENV_DEV, ENV_TESTING, ENV_STAGING, ENV_PROD],
       required: true
     },
     isActive: {