[WebGPU] Queue may try to encode blit operations on detached encoder

https://bugs.webkit.org/show_bug.cgi?id=274289
<radar://128202303>

Reviewed by Dan Glastonbury.

ensureBlitCommandEncoder needs to ensure the encoding hasn't
ended otherwise a new blit command encoder needs to be created.

Depends on #28680 for the test
to pass.

* LayoutTests/TestExpectations:
* LayoutTests/fast/webgpu/fuzz-274289-expected.txt: Added.
* LayoutTests/fast/webgpu/fuzz-274289.html: Added.
Add regression test.

* Source/WebGPU/WebGPU/Queue.mm:
(WebGPU::Queue::ensureBlitCommandEncoder):

Canonical link: https://commits.webkit.org/279026@main

LayoutTests/TestExpectations

@@ -2129,6 +2129,8 @@ webkit.org/b/139639 [ Debug ] cssom/non-subpixel-scroll-top-left-values.html [ S
 [ Release ] fast/webgpu/fuzz-274317.html [ Pass Failure Timeout ]
 [ Debug ] fast/webgpu/fuzz-274334.html [ Skip ]
 [ Release ] fast/webgpu/fuzz-274334.html [ Pass Failure Timeout ]
+[ Debug ] fast/webgpu/fuzz-274289.html [ Skip ]
+[ Release ] fast/webgpu/fuzz-274289.html [ Pass Failure Timeout ]
 
 # Imported W3C HTML/DOM ref tests that are failing.
 imported/w3c/web-platform-tests/html/dom/elements/global-attributes/dir_auto-textarea-script-N-between-Rs.html [ ImageOnlyFailure ]