bugfix: closed resource handles

[stobrien89]

Issue #, if available:
Fixes #3295

Description of changes:
After #3290, Stream objects were no longer kept alive indefinitely by circular references in our middleware stack, which caused user-provided file handles to be closed when the Guzzle streams we wrapped them with were garbage-collected.

The fix takes user-provided resource handles and uses a decorator on the Stream objects we wrap them with to detach rather than close the resource when garbage-collected.

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[stobrien89]

Smoke Tests:

vendor/bin/behat --format=progress --suite=smoke --tags='~@noassumerole'
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111 scenarios (111 passed)
222 steps (222 passed)
0m26.77s (15.14Mb)

Integ Tests:

vendor/bin/behat --format=progress --tags=integ
...................................................................... 70
...................................................................... 140
...................................................................... 210
...................................................................... 280
...................................................................... 350
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147 scenarios (147 passed)
511 steps (511 passed)
18m52.79s (702.52Mb)