Add support for general endpoint configuration for s3, to support more s3-api vendors

[tomlarkworthy]

fixes https://github.com/markusahlstrand/cloudworker-proxy/issues/123 and https://github.com/markusahlstrand/cloudworker-proxy/issues/126

Added more endpoint configuration for s3 provider. Switch to bun test to run test, enabling removal of mocha as a dependancy, and bootstrap.js to inject worker shims (bun runtime is more like CF workers by default)

[tomlarkworthy]

I think the "build (14.x)" is stuck because thats the old workflow. Maybe my previous merge did not delete it or its configured as a required step that no longer exists?

[tomlarkworthy]

turns out it was super easy to get rid of mocha and just use bun test

[tomlarkworthy]

Note the CI runs all the test https://github.com/markusahlstrand/cloudworker-proxy/actions/runs/6076062838/job/16483444708#step:5:119

[markusahlstrand]

It looks good! I'll go ahead and merge this and have a look at the other PR's