Remove base64 encoding from acir artifacts

[kevaundray]

Problem

The acir artifacts are currently being base4 encoded because they are included in the ABI.json file.

For backend end to end tests, they don't need to have a base64 encoded file since they just get the raw bytecode and not the json file.

Happy Case

base64 decode file before saving it in .bytecode

Alternatives Considered

No response

Additional Context

No response

Would you like to submit a PR for this Issue?

No

Support Needs

No response

[Savio-Sou]

cc Tooling @kobyhallx @TomAFrench @jonybur @phated

Is base64 encoding no longer needed for the E2E workflow with barretenberg (bb.js)?

[TomAFrench]

Nope, we're passing just the circuit rather than the full JSON artifact so we can pass binary.