feat: enable gpu channel async from the runtime

[deepak1556]

While investigating #240767 I see that the renderer main thread is blocked around 1s in establishing the gpu channel on the perf bot. Upstream has finished evaluation of the gpu async channel and has enabled it by default since Chromium 134 https://chromium-review.googlesource.com/c/chromium/src/+/6094045. Here is the before and after with the feature enabled, CrRendererMain is the main thread of the renderer, with the feature enabled we now push the channel establishing task to a different thread and free up main thread for other tasks.

Before:

[perf] code/willOpenNewWindow-code/willLoadWorkbenchMain: 1295ms (fastest), 1295ms (slowest), 1295ms (median)

After:

[perf] code/willOpenNewWindow-code/willLoadWorkbenchMain: 310ms (fastest), 310ms (slowest), 310ms (median)

[deepak1556]

Verified that feature is enabled from the mac exploration builds but the perf bots don't show the same wins I saw locally. Will take a look at windows tomorrow.

[bpasero]

Just a guess, but maybe its because we specifically disable GPU for the perf machines?

https://github.com/microsoft/vscode-perf/blob/4a466010310f1dcd68206b6462f46eb8b6a43d17/src/perf.ts#L144-L150

[deepak1556]

The numbers from my windows machine were with the default perf bot flags, also disable gpu only disables hw acceleration the gpu process is still used for software compositing and the channel setup will happen.

[deepak1556]

Verified on my windows machine to show improvements with the exploration build similar to the numbers from #241640 (comment)

There is definitely something else blocking the startup path on the perf machines that hides the wins from this change, I will capture traces from the perf bots as next step.