create flist server

[rawdaGastan]

Create a server to expose docker images conversion API

Related issue: threefoldtech/home#1497

[rawdaGastan]

Tasks

• add endpoint to create flist and return job ID for it to be tracked
• add endpoint to get the status of the flist using the job ID
• add endpoint to check the health of the server
• add endpoint to signin (authentication)
• add endpoint to list flists of the user. (templates are added)
• add endpoint to get the list of flists per username
• add authorization middleware to endpoints except health check
• support authentication using list of users (username and password per user)
• add server configurations (host, port, store_url, flist_dir, jwt_secret, jwt_expire, users)
• add cors for endpoints
• swagger
• add validations for request bodies
• add validations for configurations
• support progress for conversion (Support tracking progress in packing flists #69)
• preview flist (preview flist #72)
• add docker

[rawdaGastan]

• clean map of job and status for flists // to be discussed
• add pagination for listing flists support pagination and filters for listing flists #77