fix(ci): Android e2e flakes, shell Terminated sent before output (#3672)

* fix(ci): Android e2e flakes, shell `Terminated` sent before output

- close "isn't responding" system dialogs before each spec and hide error dialogs on the CI emulator:
  a launcher ANR dialog takes input focus from the app, and Android then denies clipboard reads
- retry switching to the webview context until it succeeds instead of running the spec in the
  native context when the first switch fails with "No such context found"
- save the focused window, a screenshot and logcat when an Android test fails
- shell: wait for the pipe readers to finish before emitting `Terminated`; the readers took their
  read lock on their own thread, so a child exiting quickly could have `close` emitted before
  its output

* Apply suggestion from @lucasfernog

.changes/shell-terminated-after-output.md

@@ -0,0 +1,6 @@
+---
+shell: patch
+shell-js: patch
+---
+
+Fix `Command::spawn` (and the JavaScript `Command` API) sometimes emitting the `Terminated` (`close`) event before the child's `stdout`/`stderr` output when the process exits quickly.