[TASK] Deprecate usage of @inject with non-public properties

When using private or protected properties for Dependency Injection
via `@inject`, Extbase needs to use the object reflection API to
make these properties settable from the outside, which is quite
slow and cannot be cached in any way. Therefore property injection
should only work for public properties.

Releases: master
Resolves: #82975
Change-Id: Ia9c6eb48c34c46634e626f7cd97a2e743a6aba7b
Reviewed-on: https://review.typo3.org/54618


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>