Remove soyuka/phpunit fork from all composer.json files and upgrade to
PHPUnit 12.2. Update CI workflow to install PHPUnit before other steps
and configure MongoDB conditional execution. Migrate tests from Prophecy
to PHPUnit native mocking in FieldsBuilderTest and Symfony event listener
tests. Remove unused dataprovider and fix warnings.

PHPUnit 12 requires PHP 8.3+. Widen the constraint in the root and
each component composer.json so PHP 8.2 resolves to 11.5 (LTS) and
8.3+ to 12.x. Removes the per-job "Force PHPUnit 11.5" workaround
steps from CI.

| Q             | A
| ------------- | ---
| Branch?       | 4.3
| Tickets       | ∅
| License       | MIT
| Doc PR        | ∅

Bump dev-main branch alias 4.4.x-dev -> 5.0.x-dev across root and
all 21 subpackage composer.json files. Update COMPOSER_ROOT_VERSION
to 5.0.x-dev (was stale at 4.3.x-dev).

The 4.4 branch was cut from the prior 4.4.x-dev HEAD before this bump
to carry the 4.4 maintenance line.

#7115 added cross-package calls new in 4.4 — getStateOptionsRepositoryMethod()
in api-platform/state and the repositoryMethod constructor argument in
api-platform/doctrine-common — that 4.4 provider code invokes. The old
^4.2/^4.3 sibling floors let `composer update --prefer-lowest` pull releases
lacking these symbols, so the per-component lowest CI jobs failed with
"undefined method" / "unknown named parameter".

Floor all api-platform/* inter-package constraints at ^4.4. The @Alpha
stability flag is required because the subpackages set minimum-stability:beta,
under which a plain ^4.4 would not match the 4.4.0-alpha prereleases. Revert
to plain ^4.4 once 4.4.0 stable ships.

# Conflicts:
#	.github/workflows/ci.yml

Completes 22ece5199 (open 5.0 dev line): root is 5.0.x-dev but the
self-referential api-platform/* constraints were left at ^4.4@alpha,
which is unresolvable in the component split-tests (published 4.4
alphas require metadata ^4.4, conflicting with the 5.0 root).