Add Servo integration via `--browser=servo`

[sagudev]

Split off #80 with https://github.com/ErichDonGubler/moz-webgpu-cts/pull/80#issuecomment-1967398153 taken into account. This PR only contains minimal work to acknowledge servo's existence.

It works on servo (if also used with https://github.com/sagudev/moz-webgpu-cts/commit/dddc19ded5ff7b400c4cf4a26989ab6a605b2970), but I do not have m-c clone to test with.

[ErichDonGubler]

@sagudev: Just so you know where I'm at: I'm in favor of this PR, with a few nitpicks that I'm trying to address as fixup! changes to facilitate. I'm hoping to get you feedback sometime in the next week (EDIT: welp, I did it earlier); this has been a challenge to get to with the other work I'm doing on Firefox's WebGPU team. 😅

[sagudev]

@sagudev: Just so you know where I'm at: I'm in favor of this PR, with a few nitpicks that I'm trying to address as fixup! changes to facilitate. I'm hoping to get you feedback sometime in the next week; this has been a challenge to get to with the other work I'm doing on Firefox's WebGPU team. 😅

No rush, I am currently using #80 myself to update expectations in servo, because it has all I need.

[ErichDonGubler]

@sagudev: Okay! Whew, I think I flushed my whole set of feedback here. 😮‍💨 Hope it's not too much!

I actually think that this feedback is sufficient, since I'm punting making things "perfect" to https://github.com/ErichDonGubler/moz-webgpu-cts/pull/103. If you think that the commits I've added are fine, then let's get history back down to the few commits we intend with git rebase -i main --autosquash && git push --force-with-lease. For better or worse, you are the only person who can actually do this, since the tip branch of this PR isn't part of this repo. 🙂 EDIT: Resolved.

---

_{I used Conventional Comments in this review! I hope they help with clarity and tone.}

[sagudev]

For better or worse, you are the only person who can actually do this, since the tip branch of this PR isn't part of this repo.

Actually you should be able to to that to, even if the branch is in my fork, because I have Allowing edits by maintainers enabled (I think it is by default):

Allowing edits by maintainers

If checked, users with write access to ErichDonGubler/moz-webgpu-cts can add new commits to your servo-init branch.

You can always change this setting later.

[ErichDonGubler]

@sagudev: Ahhh, I see now:

I'm so used to everybody not checking that, thanks!

[ErichDonGubler]

@sagudev: FYI: Just piggybacked a fix to CI with 062b2b9, so this could auto-merge. 🙂