[Feature]: implement usePayment composable

[Baroshem]

How the project can be improved?

Currently in some cases we are calling the api-client directly and that should be done by a composable rather than from the theme, i.e.:

    const response = await $vendure.api.setPaymentMethod({
      method: paymentMethod?.value?.code,
      metadata: {
        // Here you would pass data from an external Payment Provided after successful payment process like payment id.
      }
    });

We should develop a new composable and factory called usePayment call the api-client methods from there.

What are the acceptance criteria?

• [ ]

Additional information

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