ICU-22087 Backport: Export a non-recursive canonical decomposition supplement for ICU4X

[hsivonen]

This is a backport of #2130 to the maint-71 branch. The patch applied as-is.

Checklist

• Required: Issue filed: https://unicode-org.atlassian.net/browse/ICU-22087
• Required: The PR title must be prefixed with a JIRA Issue number.
• Required: The PR description must include the link to the Jira Issue, for example by completing the URL in the first checklist item
• Required: Each commit message must be prefixed with a JIRA Issue number.
• Issue accepted (done by Technical Committee after discussion)
• Tests included, if applicable
• API docs and/or User Guide docs changed or added, if applicable

Tests are in unicode-org/icu4x#2099

[hsivonen]

CC @sffc

[sffc]

Will merge this as soon as CI is green