tools,icu: read full ICU version info from file

* ATM on every ICU version bump we need to update these data. Reading
  it from a file makes it independant of `configre.py` changes.
* Update guide.

PR-URL: https://github.com/nodejs/node/pull/23269
Refs: https://github.com/nodejs/node/issues/23245


Reviewed-By: Steven R Loomis <srloomis@us.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>