feat: add composite action for copying to s3

[CallumNZ]

Adapted from reusable-copy-to-s3 workflow. Having it as a composite action should help address the workflow nesting limit that we see in some situations

[wilsonjord]

PR appears to add new functionality.
Last question, is the intention to reimplement the current reusable s3 workflow to use these? Or are these intended for use for those hitting the nesting workflow limit?

[CallumNZ]

PR appears to add new functionality. Last question, is the intention to reimplement the current reusable s3 workflow to use these? Or are these intended for use for those hitting the nesting workflow limit?

The driving force was the nesting limit, but yes, once this is stable we can do that for DRYness.