Modify the e2e framework to take traces as an input

[p-offtermatt]

The e2e framework should have a way to read and execute test traces given in a file.
Currently, the only way to write test traces is as go code, and this is messy to generate e.g. in MBT.
The proposition is to use a basic JSON format, but the exact format is not particularly important, as long as it is reasonable.
Noone depends on this (yet), and we can always (and will probably need to, due to different abstraction levels) write shims/drivers to go from other formats to our format.

See https://github.com/cosmos/interchain-security/tree/ph/875-use-traces-in-tests

Closing Criterion

It is possible to run the e2e tests using traces from files as inputs.

[p-offtermatt]

Reopening, since only part of this was merged so far