Add execution circuit breaker

[zbuc]

This adds a circuit break mechanism to the DEX that bounds the maximum number of path searches and position executions for any given batch swap during a block, to prevent potentially unbounded looping.

Closes #3303

[erwanor]

Will do a review on the concrete implementation, but first high-level comment: this approach is clean and I think that it follows what @hdevalence outlined on discord: a top level counter that increments function calls to path_search and fill_route.

I think my preference would be for more intrusive metering, where we reach deep into fill_route_inner and track each position we fill against. The reason for this is that a bug in the constraint resolution logic, or in the Frontier::load code, will cause a chain hang (similar to Testnet 53's) and infinite execution that the current approach would miss. With that said, I will review the approach that we have decided on here.

[erwanor]

This isn't used AFAICT?

[zbuc]

This is preliminary for the value circuit breaker

[erwanor]

Resolved some comments