message: feat: unclutter PCR primers in tree node info
  Don't show "PCR primer changes: None" when "Has PCR primer changes: No"
  Note that this affects the output tree JSON
diff: @@ -262,8 +262,10 @@ namespace Nextclade {
  newNode.setNodeAttr("Has PCR primer changes", result.totalPcrPrimerChanges > 0 ? "Yes" : "No");
  + if (result.totalPcrPrimerChanges > 0) {
  newNode.setNodeAttr("PCR primer changes",
  formatAndJoinMaybeEmpty(result.pcrPrimerChanges, formatPcrPrimerChange, ", "));
  + }
  newNode.setNodeAttr("QC Status", formatQcStatus(result.qc.overallStatus));
  