Broken move-to-end-of-word in caret mode on Windows

[The-Compiler]

With qutebrowser v3.1.0 and QtWebEngine 5.15.2, on Windows, pressing e in caret mode on tests/end2end/data/caret.html results in:

|one two three → one| two three → one two| three → one two thre|e

with the last one obviously being incorrect.

On Qt 6.2 to 6.5, the behavior got worse, with the first e jumping to one| two three, and then the cursor being stuck there (and not jumping over the space) even with further e keypresses. This looks to be due to a behavior change in window.getSelection().modify("move", "forward", "word") between Chromium 83 and Chromium 90 somewhere, though I couldn't find the exact culprit.

With "extend" in place of "move", Chromium 83 (QtWebEngine 5.15) results in one| two three → one[ two ]three as selection, but Chromium 90 results in one[ ]two three instead.

Together with our workaround here:

qutebrowser/qutebrowser/javascript/caret.js

Lines 1163 to 1168 in 4815428

	if (CaretBrowsing.isWindows &&
	(direction === "forward" ||
	direction === "right") &&
	granularity === "word") {
	CaretBrowsing.move("left", "character");
	}

which is due to Chromium following platform-specific behavior of including the trailing space:

https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/editing/editing_behavior.h;l=99-107;drc=03d34ce775fcc7578d9b2507f66f12cb05f5a205

this results in us just clearing the selection and thus further e keypresses not doing anything useful.

That in turn results in test failures on Windows:

Error: FAILED tests/end2end/features/test_caret_bdd.py::test_yank_selection_with_keep - end2end.fixtures.testprocess.WaitForTimeout: Timed out after 15000ms waiting for {'category': 'message', 'loglevel': 20, 'message': '7 chars yanked to clipboard'}.
Error: FAILED tests/unit/browser/test_caret.py::TestWord::test_moving_to_end_and_selecting_a_word[webengine] - Failed: Failed to get selection!

---

I'm not sure how to best fix this. We might need to manually inspect and adjust the selection or something to prevent the Chromium behavior. In the meantime, I'm going to adjust the tests so they don't use move-to-end-of-word I suppose...