Allowing custom tags on interaction transactions

[t8]

Hey everyone!

First off, just want to give a huge thanks to everyone who made SmartWeave possible. This is an amazing library, and we love it. With the development of Verto, we've come to realize a few things that may be beneficial to add to SmartWeave to improve the way developers interact with PSTs.

One of these realizations is allowing users to input their own tags when creating an interaction transaction with the library. For Verto especially, we like to tag on additional tags that allow us to track statistics of these transfers. Right now, unfortunately, we're having to rewrite some of our code to add this capability (and avoid using SmartWeave library interactions specifically), as seen here: useverto/trading-post#45

I figured I'd make this issue because we think that this would be useful not just for Verto and our team, but for all developers as a whole.

Thanks!