[roll pigweed] pw_web: Add a basic JavaScript REPL

The REPL supports autocomplete, command history but does not yet have
a way to call RPC ie. no `device.` global object.

Command editor is based on CodeMirror. We modify some keybindings
(like Enter to execute command, arrow up/down to view history).
Command history is stored in `localStorage`.

REPL log view is based on xterm.js.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/106171

https://pigweed.googlesource.com/pigweed/pigweed
pigweed Rolled-Commits: 1e67862f9dd32d8..29ac193641a6b62
Roller-URL: https://ci.chromium.org/b/8805369997892495089
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I9ed46e732e75f859890f7c4995b278c90fee82eb
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/zephyr-integration/+/107649
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>