COMPILE_WARNING_AS_ERROR: Add options to treat warnings as errors

Add `COMPILE_WARNING_AS_ERROR` target property and supporting
`CMAKE_COMPILE_WARNING_AS_ERROR` variable.

`COMPILE_WARNING_AS_ERROR` is initialized by
`CMAKE_COMPILE_WARNING_AS_ERROR`. It is a boolean variable. If it is
true, it expands to a different flag depending on the compiler such that
any warnings at compile will be treated as errors.

Supports compiler ids that I could find a relevant flag for.
33 files changed