tools: support full-icu by default

Instead of an English-only icudt64l.dat in the repo,
we now have icudt64l.dat.gz with all locales.

- updated READMEs and docs
- shrinker now copies source, and compresses (bzip2) the ICU data file
- configure expects deps/icu-small to be full ICU with a full
compressed data file

Fixes: https://github.com/nodejs/node/issues/19214


Co-Authored-By: Richard Lau <riclau@uk.ibm.com>
Co-Authored-By: Jan Olaf Krems <jan.krems@gmail.com>
Co-Authored-By: James M Snell <jasnell@gmail.com>
PR-URL: https://github.com/nodejs/node/pull/29522



Reviewed-By: Jan Krems <jan.krems@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>