feat(client): implement printing pages as PDF

[manuelpelloni]

This implements print page to PDF through the WebDriver2 API, which can for example be used to generate PDF documents from HTML + CSS templates.
I found the webdriver API really unforgiving, so I wrapped everything in constructors and tried to check as much as possible ahead of time.

[jonhoo]

Really good PR, thank you! Some smaller notes. I also wonder how we could write a test for this?

[manuelpelloni]

Really good PR, thank you! Some smaller notes. I also wonder how we could write a test for this?

I wrote unit tests to cover all the builder error variants and an integration test that checks the magic bytes of the PDF.

[jonhoo]

Nice, we're super close now!

[jonhoo]

Perfect, thank you! I'm going to hold off on releasing this just until #289 lands (which should be very soon) since it also has breaking changes. Thanks for sticking with it!

[jonhoo]

Ah, some of the CI is racy: fixed in #293.

Btw, easier if you merge into this MR than force-push. It makes reviews much simpler on my end. I'll still squash before merging!

[codecov]

Codecov Report

Attention: Patch coverage is 78.83212% with 58 lines in your changes missing coverage. Please review.

Project coverage is 65.24%. Comparing base (1e4d29b) to head (d19c13c).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/print.rs	81.60%	46 Missing ⚠️
src/error.rs	0.00%	11 Missing ⚠️
src/client.rs	92.30%	1 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
src/lib.rs	96.15% <ø> (ø)
src/wd.rs	65.07% <ø> (ø)
src/client.rs	63.78% <92.30%> (+0.61%)	⬆️
src/error.rs	24.87% <0.00%> (-1.20%)	⬇️
src/print.rs	81.60% <81.60%> (ø)

... and 1 file with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.