internal/pkg: collection helper-artifact

This was moved from internal/rosa because it is considered generally useful.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/rosa.go

@@ -20,9 +20,6 @@ const (
 
 	// kindBusyboxBin is the kind of [pkg.Artifact] of busyboxBin.
 	kindBusyboxBin
-
-	// kindCollection is the kind of [Collect]. It never cures successfully.
-	kindCollection
 )
 
 // mustDecode is like [pkg.MustDecode], but replaces the zero value and prints
@@ -591,29 +588,3 @@ cd '/usr/src/` + name + `/'
 		})...,
 	)
 }
-
-// Collected is returned by [Collect.Cure] to indicate a successful collection.
-type Collected struct{}
-
-// Error returns a constant string to satisfy error, but should never be seen
-// by the user.
-func (Collected) Error() string { return "artifacts successfully collected" }
-
-// Collect implements [pkg.FloodArtifact] to concurrently cure multiple
-// [pkg.Artifact]. It returns [Collected].
-type Collect []pkg.Artifact
-
-// Cure returns [Collected].
-func (*Collect) Cure(*pkg.FContext) error { return Collected{} }
-
-// Kind returns the hardcoded [pkg.Kind] value.
-func (*Collect) Kind() pkg.Kind { return kindCollection }
-
-// Params does not write anything, dependencies are already represented in the header.
-func (*Collect) Params(*pkg.IContext) {}
-
-// Dependencies returns [Collect] as is.
-func (c *Collect) Dependencies() []pkg.Artifact { return *c }
-
-// IsExclusive returns false: Cure is a noop.
-func (*Collect) IsExclusive() bool { return false }