☸️ Add support for runtime config preset in the environment property

[teroyks]

Allow defining a runtime_config preset with the environment.
Both preset ID and slug should be supported.

Example (under step configuration):

# with UUID
environment: g2.superduperlarge/f1bd21c8-ae31-451f-b75d-51cd0882aa1f

# with slug
environment: g2.superduperlarge/gpu-devices

# QOL: allow spaces for readability
environment: g2.superduperlarge / gpu-devices

[teroyks]

Note: before adding any more preset-related features, the planned simplification of preset handling should be implemented!