add support for align struct tags

[tomasweigenast]

It would be nice if this library implements something like this: https://github.com/momaek/formattag

[mvdan]

I'm not opposed to this, but - is this formatting actually widespread among Go projects? I've personally never seen it before. Given that gofupmt is meant to enforce formatting rules, I am reluctant to enforce a rule that few people try to follow already.

[PaulFarver]

@mvdan this format is enforced in the tagalign linter from https://golangci-lint.run/usage/linters/#tagalign if that is worth considering