Bring back {}, {*}, and {3} capture syntax for tuple structs/enums.

[hgzimmerman]

Description

Currently, the same syntax is used for both tuple-structs and normal structs,and unit structs.
The current implementation requires a name for each capture group, even though they aren't used for tuple-structs. A superset of the syntax could be introduced to support tuples, allowing both unnamed and named variations on the {} syntax.

To keep the implementations similar, a parameter or or type parameter could be provided to the frontend parser function.
The MatcherToken could get a superset copy of itself, or could be expanded to hold both. The advantage of keeping them separate, is that one could only produce Captures and the other one Vec<String> when matching, but would likely require a duplication of a lot of otherwise sharable logic as a downside.

[hgzimmerman]

Instead of creating a whole new parser system, just pass in an enum representing either Named / Unnamed&Unit, and special case the captures.