Fix prefill_named_grant when set via GlobusApp

[sirosen]

This uses a "nice" format of <app> on <host>. e.g.,

sample-script on porgy-and-bess

Where app_name="sample-script" and the hostname is
"porgy-and-bess".

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📚 Documentation preview 📚: https://globus-sdk-python--1075.org.readthedocs.build/en/1075/

[ada-globus]

Approving under the presumption that this was the agreed outcome of the discussion around how to handle this (since IIRC there was some disagreement). I'm a strong 👍 for use of the hostname.

[sirosen]

Yeah, this is where the discussion landed. Also, I'm pretty sure this won't conflict with other work, so I'm going ahead with the merge.