Re: Built-in CTYPE provider

* v25-0001-Address-more-review-comments-on-commit-2d819a08a.patch

This was committed.

* v25-0002-Support-C.UTF-8-locale-in-the-new-builtin-collat.patch

Looks ok.

* v25-0003-Inline-basic-UTF-8-functions.patch

ok

* v25-0004-Use-version-for-builtin-collations.patch

Not sure about the version format "1.0", which implies some sort of
major/minor or component-based system. I would just use "1".

* v25-0005-Add-unicode_strtitle-for-Unicode-Default-Case-Co.patch
* v25-0006-Support-Unicode-full-case-mapping-and-conversion.patch
* v25-0007-Support-PG_UNICODE_FAST-locale-in-the-builtin-co.patch

0005 and 0006 don't contain any test cases. So I guess they are really
only usable via 0007. Is that understanding correct?

Btw., tested initcap() on Oracle:

select initcap('džudo') from dual;

(which uses the precomposed U+01F3) and the result is

DŽudo

(with the precomposed uppercase character). So that matches the
behavior proposed in your 0002 patch.

Are there any test cases that illustrate the word boundary changes in
patch 0005? It might be useful to test those against Oracle as well.