Simple parametric tag label

Just a simple tag label that automagically adjusts size based on the text input.

#### Usage note
In order for this file to work, you ***must*** use a developer snapshot newer than 19 Aug 2021 and enable the `textmetrics` function under Edit > Preferences > Features. If you don't want (or don't know how) to do that, use the `-fallback` version instead which allows you to manually set the label length.