Camera: Initialize the forward processor along with the repeating pipeline

Some preview extensions of the image processor type expect to recevive
'onOutputSurface' calls before the session is enabled by 'onEnableSession'.

Bug: 187341271
Test: atest -c
cts/tests/camera/src/android/hardware/camera2/cts/CameraExtensionSessionTest.java

Change-Id: I67147ec24553cf87d23e33c63692fa7e59c57e5f