feat: lock on target directories not Nargo.toml

[TomAFrench]

Description

Problem*

Resolves #7542

Summary*

This PR moves the locks which are currently applied to Nargo.toml files onto the target directory. This allows users to run commands in parallel more easily without any potential for clashing by just specifying a separate build directory.

As an example of this, I've moved the integration tests to use their own target directory per test so compiling for acir/brillig and with different inliner settings don't conflict with each other.

Additional Context

Documentation*

Check one:

• No documentation needed.
• Documentation included in this PR.
• [For Experimental Features] Documentation to be submitted in a separate PR.

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[aakoshh]

In #7345 I changed the locking so when nargo is invoked on the workspace, it should still lock the individual Nargo.toml of the packages, and thus the parallel nargo compile pattern should have not experienced any contention between packages, while still writing to the common target directory of the workspace itself. Within the target directory they just wrote JSON files, so there was no other output directory to lock.

I understand your change would allow concurrent nargo compile commands to run on the same package as long as the output directory is different, so you can improve the 6 integration tests that we run for each test directory. How does it handle the workspace scenario?

[aakoshh]

I would suggest locking on a package specific lock file in the output directory, to allow the compilations in aztec-packages to go concurrently without all waiting on this single .nargo-lock to be free.

[aakoshh]

I would also suggest removing the lock files to not leave around hundreds of them, but maybe that's not important. Or maybe they can all be in a target/locks directory, so nobody is bothered.