[21.05] devhost: Add VM operation mode (PL-131470)

[leona-ya]

@flyingcircusio/release-managers

Release process

Impact: None, since only activated if the new function is explicitly enabled.

Changelog:

• devhost: Add new feature to use VMs instead of containers. The new feature is not enabled be default (PL-131470)

Security implications

• Security requirements defined? (WHERE)
  • No change for existing customer, who use the devhost feature (i.e. default operation mode should be container)
    • Container mode should still work
  • Dev VM SSH should not be accessible from outside (they use an insecure ssh key)
• Security requirements tested? (EVIDENCE)
  • New feature tested on largo and largo01
  • Dev VMs are by design not accessible from outside except https via the nginx proxy on the host - they use only internal IPv4 addresses

[leona-ya]

I don't know how to fix the pre-commit test for private keys. I think I excluded it, but it's still failing.