webgpu: backend components created and conditionally logged

[AndyHovingh]

Initial groundwork in creating WebGPU backend components, namely the instance, adapter, device, and queue.
If configured to do so, the backend will print out details about these components.
The samples/hellotriangle.cpp was slightly modified to include a webgpu option which allows for exercising the above, but does not yet draw anything to the screen/window.
NOTE: This has only been sanity tested with hello triangle on Mac OS and the Android emulator at this time, NOT IOS, Windows, or Linux yet.

BUGS = [400212369]

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[AndyHovingh]

This seems ok to me as long as we can assume the platform will always outlive the driver. We need to verify that assumption,.

[AndyHovingh]

@poweifeng is this a fair and safe assumption that the platform should always outlive the driver?

[jneljneljnel]

lgtm

[AndyHovingh]

@poweifeng note that we just ran into a snag when rebasing where we get some runtime errors as a result of WebGPUDriver.cpp indicating the shader language is WGSL (as opposed to ESSL3). But, I did not want to have that hold up getting some feedback on the PR as we address it.

ShaderLanguage WebGPUDriver::getShaderLanguage() const noexcept {
    return ShaderLanguage::WGSL;
}

update:
@bridgewaterrobbie proposed a good solution, which involves waiting for #8516 to get merged first and adding webgpu support in the sample and common material generation (when webgpu support is configured on) (+ a few small things, such as variant filter, to ignore known tint WGSL code gen issues). That's the plan.