Camera3StreamSplitter: Refactor to completely eliminate IGBP/IGBCs

This change is pretty comprehensive. It includes the following changes:

- Surface are used instead of IGBPs everywhere
- Equivalent APIs and delgates are used everywhere
- mInputSlots is removed (slots don't exist anymore)
- mOutputs is removed. mOutputSurfaces is used instead
- mFrameNumber tracking is removed (done by ConsumerBase)

See: go/warren-buffers

BYPASS_IGBP_IGBC_API_REASON: this CL is part of the migration.

Bug: 340933206
Flag: com.android.graphics.libgui.flags.wb_stream_splitter
Test: atest, presubmit, compiles

Change-Id: Ib0eb5abd3dd430e78977dd1f5093268ff4c748e4