Make the file download delegate sendable #128

Job	Run time
Cxx interop / Construct Cxx interop matrix	3s
Unit tests / Construct unit test matrix	5s
Soundness / Documentation check	52s
Soundness / License headers check	5s
Soundness / API breakage check	52s
Soundness / Unacceptable language check	4s
Soundness / Broken symlinks check	2s
Soundness / Format check	34s
Soundness / Python lint check	6s
Soundness / Shell check	33s
Soundness / YAML lint check	3s
Static SDK / Static SDK / Linux (latest-release Jammy)	1m 2s
Static SDK / Static SDK / Linux (main Jammy)	1m 3s
Cxx interop / Cxx interop / Linux (5.10)	1m 5s
Cxx interop / Cxx interop / Linux (6.0)	1m 5s
Cxx interop / Cxx interop / Linux (6.1)	1m 2s
Cxx interop / Cxx interop / Linux (nightly-next)	1m 4s
Cxx interop / Cxx interop / Linux (nightly-main)	1m 5s
Unit tests / Unit tests / Linux (5.10)	54s
Unit tests / Unit tests / Linux (6.0)	54s
Unit tests / Unit tests / Linux (6.1)	53s
Unit tests / Unit tests / Linux (nightly-next)	54s
Unit tests / Unit tests / Linux (nightly-main)	55s
	15m 15s

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