fix: don't accept extra fields inside the currency options on create

[fivism]

In order to save and retrieve dineros to/from our storage layer we map them to a copycat money-type. However, on retrievals we noticed that internal fields were leaking into the currency objects like so:

"amount": 0,
"currency": {
    "_type": "currencyObj",  <----
    "base": 10,
    "code": "USD",
    "exponent": 2
},
"scale": 2

... and upon further investigation one can pass anything into a dinero's currency object as long as the required subset of fields is met. This change makes the selection of fields as explicit as the base structure's (where amount, currency and scale are taken and everything else ignored).

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Name	Status	Preview	Updated
dinerojs	✅ Ready (Inspect)	Visit Preview	Nov 18, 2022 at 11:08PM (UTC)

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[sarahdayan]

Good one, thanks!

I left two minor comments, then we'll be good to go.

[sarahdayan]

Thanks for your contribution @fivism!