This change is similar to:
* https://github.com/flutter/flutter/issues/82728
* https://github.com/flutter/flutter/issues/87073

We are using a more recent Chromium ICU fork commit.

See for reference: https://chromium.googlesource.com/chromium/deps/icu

Flutter needs to use a reasonably recent version of the ICU library. The
Chromium's fork of ICU, which is in use in Flutter as well, has taken in
a few updates since the initial 69.1 release.

Update the DEPS file in github.com/flutter/engine to use the commit ID
`a38aef9142ace942a8bf166020c569f4cda0f8d3` for the ICU library.

This takes in recent patches to the ICU library, most relevant of which
is a fix for Norwegian language support.

Fixes: #flutter/flutter/88600

See https://github.com/flutter/engine/pull/27920

This contains a fix needed to build with the latest Clang toolchain.

This eliminates use of third_party/gyp.

This reverts commit a116cc0d.

This reverts commit 19f639db.