Use stellar-core upgrade config set command

[leighmcculloch]

What

Use stellar-core upgrade config set command to set Soroban config instead of using the high limit override.

Why

The high limit override is good, but it is a blunt configuration that only allows setting a single high limit. When it is off the limit is so low it is unusable. There is no way to configure custom limits, or limits that mirror pubnet/testnet/etc.

While this PR doesn't make it configurable, it makes it possible for us to change quickstart's limits, and in a follow up PR we can add options like --enable-unlimited-limits or --enable-testnet-limits. At the moment the PR simply uses testnet limits from a .json file.

Close #508

[leighmcculloch]

@sisuresh @tsachiherman Looking for your review of this PR. I'm not marking it as ready because I don't want it merged yet because it's still using an unreleased version of stellar-core from @sisuresh's fork. Before merging I'll want to update it to use a patch release of stellar-core.

But what I'm looking for review is your thoughts. This PR doesn't leave this in a state that I think is perfect. It's somewhat brittle, although I'd done my best to expose statuses, logs, and check for success as best as possible, without introducing dependencies on more services being up at this point of the upgrade being done.

Not entirely proud of it, but I think this is an area we can improve on down the line and I think this is probably just stable enough for dev/testing.

[leighmcculloch]

This change introduces a ~6 second delay into friendbot startup, because friendbot startup is delayed until after network config completes, because network config and friendbot use the same account.

I think we'll accept that as an acceptable slow down that'll get better once we can reduce the 4 async steps of config down to 2 via a built-in deployer contract or a built-in config updater contract. cc @dmkozh

[tsachiherman]

Overall, I think the change is good.
I'd rather seeing us using release core versions rather then private branches.

[leighmcculloch]

I'd rather seeing us using release core versions rather then private branches.

The PR is temporarily using @sisuresh's PR to validate that it works end to end before we merge and release stellar-core. We need to do more early validation imo.

This PR won't be merged until the change in the form is released, which will be hopefully soon in a patch 🙏.

[leighmcculloch]

I'd rather seeing us using release core versions rather then private branches.

This change is using stellar-core v20.0.0-rc.2.2 now.