Partial image rebuilds

[kwabenantim]

Summary

Consider adding a github workflow to update a single dependency in a docker image without rebuilding everything else. Currently, all dependencies in an image need to be rebuilt, even when only one dependency is being updated.

For example if we only want to change the version of PETSc in the portability-dev image, the workflow should:

• Remove the old PETSc version from the current portability-dev image.
• Build the new PETSc version into the image.
• Keep all the other dependencies in place.