When using SAPI from an external project via CMake, the small zlib patch
cannot be found during the config phase.
This change also fixes an oversight in that the tests depend on some of
the example code.
Regardless embedding code should set `SAPI_ENABLE_EXAMPLES` to `OFF`.
Disabling tests by setting `SAPI_ENABLE_TESTS` to `OFF` stays optional.
PiperOrigin-RevId: 311290454
Change-Id: Ibe105895859b793b20f47c89b1a9e11cbfef2e2f