easy-install upgrade command

[NagariaHussain]

The upgrade command could be simplified with defaults for image and version:

./easy-install.py upgrade --project=insights_prod_setup --image=ghcr.io/frappe/insights --version=stable --backup-schedule="@every 2m"

Also can we have a better way to update frappe_docker contents itself? Deleting and re-creating (script does that) resulted in loss of .env file. Or should we move this file somewhere else?

Originally posted by @NagariaHussain in #1609 (comment)

[revant]

• move image and tag from in-memory variables to .env file
• move frappe_docker/.env to ~/<project-name>.env
• move ~/passwords.txt to ~/<project-name>-passwords.txt