embedlite-components-next153

- Rebuild the extension bindings on the toolkit base classes, following Firefox for Android: real TabTracker, TabBase, TabManager, Window and WindowManager subclasses in place of hand-written stubs. Tab ids are handed out per content window instead of being fixed at 1. - Add a browsingContext getter to the tab wrapper, so frameId and allFrames resolve against the page rather than the stand-in embedder element. Cookie banners live in subframes and were never reached before. - Honour Chrome-style callbacks in tabs.query, get, insertCSS, removeCSS and executeScript. Extensions written for Chrome wait for the callback rather than the promise, and the schema layer that normally translates is bypassed by these hand-written entry points, so callers waited forever. - Force author-origin sheets in insertCSS: user sheets are accepted by addSheet but never take effect here, so cookie blockers asking for "user" silently did nothing.