1) Mark the following GSL features as deprecated:
- gsl::unique_ptr (always)
- gsl::shared_ptr (always)
- gsl::byte (since c++17)
- gsl::joining_thread (never implemented)
2) Refactor existing deprecations to use the new GSL_DEPRECATED(msg) macro.
3) Create a section in the README for deprecated features in the
standard.
* this commits adds tests that should fail, but don't
* Better use of std::enable_if
Replace the occurances of `class = std::enable_if_t<Cond>` and `typename = std::enable_if_t<Cond>` that have been identified in the previous commit with `std::enable_if_t<Cond, bool> = true`.
This commit is inspired by #1174, which changed one occurance in the owner header. This commit is aimed to fix all remaining occurances.
* fix failing checks
- core.cxx_gsl aktualisiert auf [](https://gitlab.avm.de/fos/repos/core.cxx_gsl/-/commit/)
- plc.access_lib aktualisiert auf [](https://gitlab.avm.de/fos/repos/plc.access_lib/-/commit/)
- plc.common aktualisiert auf [](https://gitlab.avm.de/fos/repos/plc.common/-/commit/)
- plc.daemon aktualisiert auf [](https://gitlab.avm.de/fos/repos/plc.daemon/-/commit/)
-
Test Plan:
-
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Co-authored-by: Werner Henze <werner.henze+gitcommits@posteo.de>
Co-authored-by: Werner Henze <w.henze@avm.de>
