Add support for pre-built instance docker images

[timesler]

Description of changes: This PR adds support for pre-built per-instance docker images, hosted on GHCR.

Detail:

• Adds a script that was used to build and upload the images
• Updates the evaluation harness get an appropriate image by:
  1. Checking for an existing local image for the instance
  2. Attempting to pull a pre-built image from ghcr.io/timesler/swe-polybench.eval.x86_64.{instance_id}:latest
  3. Fallback to current local docker image build solution
• No changes have been made to the usage of the harness

The changes to the actual harness code are minimal, and relate only to checking for and using a prebuilt image if it exists.

State of pre-built images:

• Currently, the first half (approx) of PB500 has been pushed and is available
• Should have the remaining images ready in the next few days

Testing:

• I have run the harness with the Gold patches successfully on the first ~150 or so instances in the dataset using prebuilt images, and will complete the evaluation over the next few days as the additional images are push and made available

Backward compatability:
The way this change has been implemented, it will work whether an instance has a pre-built image available or not, so can be used as is today.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[mshihabr]

LGTM! Thanks for uploading the scripts as well!