move Fast USDC into its own repo

[turadg]

What is the Problem Being Solved?

Fast USDC is not part of the Agoric SDK but was built in the agoric-sdk repo as a convenience. Other developers need to build things like Fast USDC without making changes to agoric-sdk, but that's very difficult.

Description of the Design

Pull the @agoric/fast-usdc package into its own repo.

For each of these integration test suites, developing tooling to run them outside agoric-sdk and then move the existing tests to the new repo to use them.

• Bootstrap/RunUtils (boot/test/fast-usdc)
• a3p-integration (proposals/f:fast-usdc)
• multichaint-testing (multichain-testing/test/fast-usdc/)

Security Considerations

Scaling Considerations

Test Plan

Upgrade Considerations