Add set num to tokens.xml

[SlightlyCircuitous]

This PR adds a set number attribute (num) to every token printing that was physically printed in a set. Custom tokens, blog tokens, and tokens only found on Arena don't have set numbers (at least not that I can tell) and so have not received this attribute. I assigned almost all of these nums programmatically, by looking up the UUID on Scryfall. However, A Mysterious Creature, Cyberman, Morph, and Manifest are type:Creature and are additionally difficult to search for on Scryfall, so I have done those 15 printings manually.

There are two reasons to do this:

• The client currently lists the set number for cards and tokens in the Card Info box; set number is currently always blank for tokens and this would fill those fields in
• Lookup by set num was requested in Add UUIDs to the Tokens File #340 (comment) and this provides preliminary XML support in the event this is implemented in the client

I am currently uncertain what (if anything) to do about tokens that do not have an official set number and open to suggestions, but this PR at least solves the above issues for the majority of the file.

[Psithief]

What % of printed tokens don't have a number on the printing? (Rough estimate)

[SlightlyCircuitous]

There are 2348 unique printings in the tokens file and 79 of them don't have a num, so that's about 3%. It's the same number that don't have a uuid, in fact.

Unless you mean 'what % of tokens actually printed in paper by WotC don't have a num?', in which case the answer is 0.

[Psithief]

what % of tokens actually printed in paper by WotC don't have a num

Yes, it was this. I wasn't sure if the earliest tokens had been printed with a number.

[ebbit1q]

I see no reason not to merge this, it might be useful somewhere and the file size increase is marginal

[SlightlyCircuitous]

I will update this with set nums for the SLD and FIN tokens arts that were recently merged in from #347 and #351

[SlightlyCircuitous]

Ran the new tokens.xml file through my Collector Numbers script in order to add in FIN and SLD nums. This had the side effect of adding the recent reverse-related changes to this PR as well. I can remove them if it's detrimental. I can also just close this and reopen a fresh PR if that's easier to handle.

[SlightlyCircuitous]

Closed in favor of #355