Pass a build's drv path as a store path

Dependencies

• [2] H3S3H752 Pass along drvPath and outputName for inputs that are previous builds.
• [3] CQTN62OH Die tabs die
• [*] OOQ2D3KC * Refactoring: move fetchInput out of hydra_scheduler into a separate

Change contents

• replacement in src/lib/Hydra/Helper/AddBuilds.pm at line 291
  [2.278]→[2.278:367](∅→∅)
  − (defined $input->{drvPath} ? "; drvPath = " . $input->{drvPath} . "" : "") .
  [2.278]

  [3.4114]
  + (defined $input->{drvPath} ? "; drvPath = builtins.storePath " . $input->{drvPath} . "" : "") .