Add rclone copy stage

[jbusecke]

• Test functionality (Finalize recipe (+ test new rclone copy stage) chirps_feedstock#1)
• Add remove_endpoint_url logic (see https://github.com/leap-stc/chirps_feedstock/blob/bcf0561d7c7ea193262260500fc9f0d354a20746/feedstock/recipe.py#L56-L57)
• Archive https://github.com/leap-stc/test-transfer
• Document difference between this and old copy stage. Decide on what to do with the old one.
• Test rclone and raise good error on failure.

[jbusecke]

Moved the entire config to env variables to avoid accidentally printing the secrets in case of an error.

[jbusecke]

Ahhh I just realized that we were using the custom image "quay.io/leap-stc/rclone-beam:2024.09.24" in the test case.
It is kind of a bummer that we now have to specify that in the feedstock (disconnected form this stage). It just took me a while to understand what the issue here](leap-stc/chirps_feedstock#1) was (rclone is not installed). I guess we need a better way to detect this issue here?

[jbusecke]

Ok nice I was able to read this (authenticated, cause this is just a test bucket) from OSN:

import xarray as xr
import s3fs
fs = s3fs.S3FileSystem(profile='osn-m2lines-test', client_kwargs={'endpoint_url': 'https://nyu1.osn.mghpcc.org'})
fs.ls('m2lines-test')
mapper = fs.get_mapper("m2lines-test/test-rclone-stage/chirps-global-daily.zarr")
xr.open_dataset(mapper, engine='zarr')

Lets finish this bad boy.