`EGL14` was added in API 17, so move all references into the `Api17` wrapper
class. `GLES30` requires API 18.
Remove some defensive calls to check that a context is current. Checking for GL
errors after calls should catch the case of calling GL methods without a
context (which is also only likely to come up early in development), and these
checks were not done consistently across all methods anyway. That allows
removing the API 17 requirement from `SceneRenderer` (where previously it
wasn't documented).
PiperOrigin-RevId: 548669946
81ef52763d