feat: Pay before Persist experiment

[MantisClone]

Towards #1331
Related #1251

Problem

In theory, we can Pay a request before persisting it in the Request Network protocol.

In other words, we create a Request in memory without persisting it. Then, we prompt the end user to send payment against that request. Finally, we persist the request - so that it may serve as a receipt for the payment.

However, the existing SDK functions assume that the request is persisted immediately after being created.

Motivation

This shortens the critical path for a user making a payment. This is especially desirable for payment apps - in which a payer wants to buy something. The workflow is driven by the payer instead of the payee, so why make them wait for the request to be persisted before allowing them to send a payment?

Changes

• feat: public funcs for creating a request in memory without persisting

Why were these variables/functions chosen?

I traced the RequestNetwork.createRequest() and the RequestLogic.acceptRequest() functions and changed all the internal variables/functions private => public.

Considerations

Rather than implementing this new logic, this PR only changes several private functions and variables to be public, thus empowering external contributors to experiment with the "Pay before Persist" workflow. The expectation is that once these experiments are complete, we either:

1. Revert this PR
   or
2. Implement the "Pay before Persist" functions in the RN SDK.

[MantisClone]

@limone-eth Here's the PR that will enable your Pay before Persist experiment.