detach -> release
The C++ standard library uses the name "release" for the operation we call "detach".
Rewriting each "detach(" to "release(" brings us a step closer to using standard library types directly (e.g. std::unique_ptr instead of SkAutoTDelete).
This was a fairly blind transformation. There may have been unintentional conversions in here, but it's probably for the best to have everything uniformly say "release".
BUG=skia:
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1809733002
Review URL: https://codereview.chromium.org/
1809733002