Surface: Provide more useful/platform-y buffer methods

These will be easier to use than having to use ANativeWindow
equivalents.

BYPASS_IGBP_IGBC_API_REASON=warren buffers

Flag: com.android.graphics.libgui.flags.wb_platform_api_improvements
Bug: 340933794
Test: new libgui_test tests, atest
Change-Id: I0343abb45aadf708ef6115fa108a3b4c402cfd47