chore: abort pending operations upon disconnect

[dgozman]

This involves a few changes:

• protocol cleanup as every channel is now "progress: true";
• keeping ProgressController instances of ongoing operations inside the dispatcher;
• replacing Dispatcher._openScope with aborting progress controllers;
• instead of issuing stopPendingOperations() when disconnecting from a reused context, we call an explicit disconnectFromReusedContext() method;
• various small cleanups.

References #35987.

[github-actions]

Test results for "tests 1"

2 failed
❌ [webkit-library] › library/video.spec.ts:441:5 › screencast › should work for popups @webkit-ubuntu-22.04-node18
❌ [webkit-page] › page/page-event-popup.spec.ts:28:3 › should work with window features @webkit-ubuntu-22.04-node18

10 flaky

⚠️ [chromium-library] › library/chromium/tracing.spec.ts:49:3 › should run with custom categories if provided @chromium-ubuntu-22.04-node20
⚠️ [firefox-library] › library/inspector/cli-codegen-1.spec.ts:1087:7 › cli codegen record › should not throw csp directive violation errors @firefox-ubuntu-22.04-node18
⚠️ [firefox-library] › library/inspector/pause.spec.ts:74:5 › pause › should pause and resume the script with keyboard shortcut @firefox-ubuntu-22.04-node18
⚠️ [firefox-page] › page/page-event-request.spec.ts:182:3 › should return response body when Cross-Origin-Opener-Policy is set @firefox-ubuntu-22.04-node18
⚠️ [playwright-test] › ui-mode-test-watch.spec.ts:145:5 › should watch all @ubuntu-latest-node22-1
⚠️ [playwright-test] › ui-mode-test-watch.spec.ts:145:5 › should watch all @ubuntu-latest-node24-1
⚠️ [webkit-library] › library/browsercontext-viewport-mobile.spec.ts:97:5 › mobile viewport › should fire orientationchange event @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › library/screenshot.spec.ts:55:14 › page screenshot › should work with a mobile viewport and clip @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › page/page-screenshot.spec.ts:345:5 › page screenshot › should work while navigating @webkit-ubuntu-22.04-node18
⚠️ [playwright-test] › ui-mode-test-watch.spec.ts:145:5 › should watch all @windows-latest-node18-1

47093 passed, 980 skipped
✔️✔️✔️

Merge workflow run.