[typeless-sample-bot]: Add an alternate tagging method to catch samples outside the sample browser

[feywind]

At the moment, the typeless-sample-bot only finds samples that have the // [START foo] tag in them. Unfortunately this also makes them show up in the sample browser, even when we don't have a foo ready for them (or do not intend to make one).

My intent is to add another regex to the typeless bot that it can look for to detect a sample it should munge into JS.