RunCommand: emit the `finished` field as a boolean

Dependencies

• [2] 6ZXL5UOP Add a plugin to execute arbitrary commands when a build finishes
• [3] 3AKZKWCR RunCommand: Test
• [4] E4TV6NH6 RunCommand: pass homepage, description, license, system, and nixname
• [5] YIZWKGFI tests: add jobsdir and testdir to ctx hash
• [6] OAGCZHK6 Allow for precisely one instance of RunCommand plugin

Change contents

• replacement in src/lib/Hydra/Plugin/RunCommand.pm at line 65
  [2.1479]→[2.1479:1539](∅→∅)
  − finished => $build->get_column('finished'),
  [2.1479]

  [2.1539]
  + finished => $build->get_column('finished') ? JSON::true : JSON::false,
• replacement in t/plugins/runcommand.t at line 56
  [3.2949]→[3.2949:3001](∅→∅)
  − is($dat->{finished}, 1, "The build finished.");
  [3.2949]

  [3.3001]
  + is($dat->{finished}, JSON::true, "The build finished.");