Call super().build(input_shape) instead of self.built = True in all Keras layers.

[copybara-service]

Call super().build(input_shape) instead of self.built = True in all Keras layers.

Within build(), some Keras layers where calling super().build(input_shape) while some were calling self.built = True. This would result in a different config when serializing whereby layers doing self.built = True would not have a build_config.

This change makes it consistent between all the layers as well as consistent with Keras 3.

Note that some layers need to call Layer.build(self, input_shape) directly to bypass some class' build() but still populate the information for the build_config.