[epic] add support for AuthNext

[tsachiherman]

What ?

This is the epic ticket for the AuthNext support changes for the platform team.

The following are the dependent issues:

Completed

• xdr: update go monorepo XDR #347 [1 story points]
• soroban-rpc: Update SimulateTransaction code to support authNext #348 [3 story points]
• Add strkey parsing for contracts, and Address helper for building ScAddresses js-stellar-base#572
• https://github.com/stellar/go/issues/4757 [3 story points]
• https://github.com/stellar/go/pull/4760
• soroban-cli: update soroban-cli to support AuthNext #349 [5 story points]
• js-soroban-client: update to support AuthNext #350 [5 story points]
• dapp example: update to support AuthNext #351 [3 story points]

In Progress

• Update system test to support AuthNext changes system-test#19 [5 story points]

Next

[mollykarcher]

I'm going to close this. The system-test change is technically still pending, but it is merged and just waiting for next release