New Endpoints For block "Apps"

[ruslanfirefly]

I implemented main endpoints for new new block "Apps":

• List All Apps
• Create a New App
• Delete an App
• Retrieve an Existing App
• List App Deployments
• Create an App Deployment
• Retrieve an App Deployment
• Cancel a Deployment

[ruslanfirefly]

@trmcnvn hi, please review PR. I fixed some problems in tests but i'm not sure about correct approach

[trmcnvn]

Thanks