Adds initial support for external attachments using the Filesystem or MinIO #3216

Job	Run time
build_and_test (3.11, 22.x, :lint:python:client:common:smoke:stubs:)	4m 54s
build_and_test (3.11, 22.x, :lint:python:client:common:smoke:stubs:)	4m 54s
build_and_test (3.11, 22.x, :server-1-of-2:)	8m 32s
build_and_test (3.11, 22.x, :server-1-of-2:)	8m 32s
build_and_test (3.11, 22.x, :server-2-of-2:)	9m 49s
build_and_test (3.11, 22.x, :server-2-of-2:)	9m 59s
build_and_test (3.11, 22.x, :nbrowser-^[A-D]:)	10m 24s
build_and_test (3.11, 22.x, :nbrowser-^[A-D]:)	10m 53s
build_and_test (3.11, 22.x, :nbrowser-^[E-L]:)	9m 24s
build_and_test (3.11, 22.x, :nbrowser-^[E-L]:)	9m 37s
build_and_test (3.11, 22.x, :nbrowser-^[M-N]:)	11m 48s
build_and_test (3.11, 22.x, :nbrowser-^[M-N]:)	11m 48s
build_and_test (3.11, 22.x, :nbrowser-^[O-R]:)	7m 7s
build_and_test (3.11, 22.x, :nbrowser-^[O-R]:)	7m 7s
build_and_test (3.11, 22.x, :nbrowser-^[^A-R]:)	7m 48s
build_and_test (3.11, 22.x, :nbrowser-^[^A-R]:)	7m 48s
build_and_test (:lint:python:client:common:smoke:, 22.x, 3.10)	4m 40s
build_and_test (:lint:python:client:common:smoke:, 22.x, 3.10)	4m 40s
candidate	0s
candidate	0s
	2h 29m 44s

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