Any-chain, any coin request

[dcposch]

Goal

Allow request deeplinks that specify a destination chain.

This allows, for example, 1-tap checkout to a store using Optimism USDC.

Follow up to #1250
Part of #490

Proposed solution

Current requestV1 (untracked) deeplink:

https://daimo.com/l/request/ansgar.eth/4.20/555

Updated:

https://daimo.com/l/request/ansgar.eth/4.20?c=10&t=USDC

Or:

https://daimo.com/l/request?to=ansgar.eth&n=4.20&c=10&t=USDC

https://daimo.com/l/request?to=ansgar.eth&n=4.20&c=10&t=USDC&memo=Media+Luna

...we can update requestV2 later. These are more complex, since they involve onchain tracking of whether a request has been paid. Creating a request onchain, eg on Base, with a parameter that specifies that you want to receive payment on another chain seems incorrect.

For one-tap checkout, all we need is a requestV1 with destination chain and coin prefilled.