Pack doesn't mount provided volume when using creator

[simonjjones]

Summary

When building an image using a trusted builder pack now uses a single creator lifecycle phase container to perform all operations. When the --volume argument is passed, this is generally used to instantiate containers for the individual phases that need it. This argument is currently not being respected when initializing a creator phase.

---

Reproduction

Steps

1. If we return the acceptance tests for mounting volumes to their original states, expecting the messages to include the file contents some-string the tests will fail

...
---> DETECTING
        ======== Output: volume/bp@volume-bp-version ========
        ---> Detect: Volume Buildpack
        /cnb/buildpacks/volume_bp/volume-bp-version/bin/detect: line 9: /platform/my-volume-mount-target/some-file: No such file or directory
        Detect: Reading file '/platform/my-volume-mount-target/some-file':
        ---> Done
        ...
        ---> BUILDING
        ---> Build: Volume Buildpack
        /cnb/buildpacks/volume_bp/volume-bp-version/bin/build: line 9: /platform/my-volume-mount-target/some-file: No such file or directory
        Build: Reading file '/platform/my-volume-mount-target/some-file':
        ---> Done
...
to contain 'Detect: Reading file '/platform/my-volume-mount-target/some-file': some-string'
...

Current behavior

Creator is not mounted with the expected bind configured with --volume leading a buildpack that expects to find mounted content unable to read it.

Expected behavior

Creator is mounted with the bind configured with --volume, a buildpack can read content from this volume

---

Environment

Acceptance tests