internal/pkg: expose response body

This uses the new measured reader provided by Cache. This should make httpArtifact zero-copy.

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

internal/pkg/file.go

@@ -2,7 +2,6 @@ package pkg
 
 import (
 	"bytes"
-	"context"
 	"crypto/sha512"
 	"fmt"
 	"io"
@@ -54,6 +53,6 @@ func (a *fileArtifact) Checksum() Checksum {
 }
 
 // Cure returns the caller-supplied data.
-func (a *fileArtifact) Cure(context.Context) (io.ReadCloser, error) {
+func (a *fileArtifact) Cure(*RContext) (io.ReadCloser, error) {
 	return io.NopCloser(bytes.NewReader(*a)), nil
 }