Swift: Honor CMAKE_EXE_LINKER_FLAGS when CMP0157 is NEW

Since commit 56e5cea600 (Swift: Support module libraries with
command-line build systems, 2024-03-23, v3.30.0-rc1~245^2) we pass
`CMAKE_SHARED_LINKER_FLAGS` when linking Swift shared libraries if
CMP0157 is NEW.  For consistency, pass `CMAKE_EXE_LINKER_FLAGS` when
linking executables.  Add policy CMP0214 for compatibility.

Fixes: #26154