add ephemeral_storage to resources decorator

[nick-macro]

Add the ephemeral_storage parameter to the resources decorator. Related to this Slack thread.

It deviates from the suggestion to alias disk in resources because disk is in units of MiB and ephemeral_storage is in units of GiB. This means that these two would not be the same behavior.

size = 50
# not equal behavior
resources(disk=size)
batch(ephemeral_storage=size)

# equal behavior
resources(ephemeral_storage=size)
batch(ephemeral_storage=size)