Adam Mason’s schlocky and opportunistic “Songbird” is billed as the first Hollywood feature to be made during quarantine, and this impressively scaled pandemic-themed riff on “The Purge” couldn’t be prouder of itself for that accomplishment. The project announces its own topicality before the studio company logos have even played out during the opening credits, as snippets of news audio bark at us about the death toll of COVID-23 (a mutated coronavirus that’s evolved to attack brain tissue and kill people within 48 hours of infection), and not a single minute of the slapdash movie that follows allows you to forget that it was conceived, pitched, written, shot, edited, and released since lockdown started in March.