non-standard data arguments

[topepo]

In some cases, a model function that parsnip is calling has non-standard argument names for the data-oriented components.

For example, a function foo() that only has the x/y interface might have a signature like foo(X, Y) instead of the standard foo(x, y).

Some real examples:

• sparklyr models use x as the data slot (and put it in the first position)
• kernlab::ksvm(x, data) where x is a formula.
• MASS::lda(x, grouping)

[juliasilge]

This change is implemented in #316. 🚀

[github-actions]

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