`SFMLConfig.cmake` uses the `if(... IN_LIST` feature which requires
policy `CMP0057` to be enabled (added in CMake 3.3). If an application
uses `find_package(SFML)` with a minimum CMake version set to less
than `3.3`, the `IN_LIST` lines cause a CMake error.

Fix this by setting the minimum CMake policy we require in
`SFMLConfig.cmake`. CMake keeps a policy stack so this does not affect
the application's policy.

Commit e512771 ("Install pkgconfig only if module is built")
attempted to move the pkg-config installation rules into
`sfml_add_library`, but this fails if `SFML_PKGCONFIG_INSTALL_DIR` is
unset because this code is run before the default value is set in
`CMakeLists.txt`.

Fix by moving the `add_subdirectory(src/SFML)` line below the
pkg-config setup code.

Closes: #3504

…objects. Fixes #3503

The llvm 21 release adds a new on by default warning for charN_t
implicit conversion. This adds a static cast to get around that.

Adds the necessary warning about macOS 'Accessibility' permission requirements for the setPosition functions, addressing the remaining part of issue #3533.