* op-deployer: Separate L1 and L2 contract artifacts

Adds support for specifying separate artifact URLs for L1 and L2. There are two new fields in the intent - `L1ContractsLocator` and `L2ContractsLocator` - which together replace the `ContractArtifactsURL` and `ContractsRelease` fields. Specifying a file or HTTPS URL for either field will automatically enable dev mode for the deployment. Specifying a `tag://` URL will use the standard deployment for L1 and L2. The default have been set to the following:

- L1: `op-contracts/v1.6.0`
- L2: `op-contracts/v1.7.0-beta.1+l2-contracts`

Fixes https://github.com/ethereum-optimism/platforms-team/issues/337.

* fix test

* fix another test