IBX-12530: Deprecated the schema-file API and moved DatabaseSchemaHook onto SchemaApplier

[Steveb-p]

Warning

This branch includes a temporary commit (dependencies.json) that points CI at
ibexa/doctrine-schema#49 so tests can run before that PR merges. Must be removed before
merging this PR.

🎫 Issue	IBX-12530

Related PRs:

• IBX-12530: Added SchemaApplier for executing a built Schema against a connection doctrine-schema#49 — hard dependency; adds the SchemaApplier used here
• IBX-12530: Built IbexaKernelTestTrait schema from SchemaBuilderEvent core#823 — the same move for IbexaKernelTestTrait::loadSchema()
• IBX-12530: Allowed Bootstrapper to run against any KernelInterface, not just IbexaTestKernel #44 — this is stacked on it (which is stacked on IBX-12530: Rebuilt DatabaseSchemaHook on SchemaBuilderInterface instead of a raw-file reimplementation #43)

Description:

Tidy-up after #43, deliberately kept out of #43 so that PR — which 26 package PRs depend on —
does not acquire a dependency on an unmerged ibexa/doctrine-schema PR.

Two things:

DatabaseSchemaHook uses SchemaApplier. It reimplemented the same toSql()-and-execute loop
that ibexa/core's LegacySchemaImporter has; both now call doctrine-schema's new applier. The hook
passes $dropExistingTables = false, since Bootstrapper always hands it a freshly created
database. RemoveUnsatisfiableHooksPass gains SchemaApplierInterface in the hook's requirements,
so a kernel without DoctrineSchemaBundle still drops the hook cleanly rather than failing to
autowire.

DefaultSchemaFilesProvider and IbexaTestKernel::getSchemaFiles() are deprecated. Nothing in
this package reads either any more — the schema comes from SchemaBuilderEvent, so whichever
bundles a kernel registers is what the schema contains. They are deprecated rather than removed
because Ibexa\Contracts\Core\Test\IbexaTestKernelInterface still mandates getSchemaFiles(), and
ibexa/core's IbexaKernelTestTrait kept reading it until ibexa/core#823. Removal is a 6.0 job, and
wants to happen in step with that interface.

For QA:

composer test — 39 tests / 92 assertions, unchanged. PHPStan and code style clean.

End-to-end against a real consumer, with this branch and doctrine-schema#49 both symlinked in:
ibexa/dam-user gives 11 / 19, identical to what it gives against #43 alone — so routing the hook
through SchemaApplier produces the same schema.

Note this branch also merges in the current tip of #43. #44 was cut before #43 gained the
IbexaTestKernel bundle registration, so both #44 and this branch were missing it; #44 has been
updated too. Without it a consumer's schema comes out empty, which is exactly how this was caught.