Mid-execution replay starts the replay from a specific start frame
instead of frame 0. Integration tests will then run between the start
and end frames. This lets us make much smaller reproduction cases from
large benchmarks or applications.

We implement mid-execution replay via a cpp "Setup" function. The
replay test will run the setup function before the starting frame. Test
execution proceeds normally after setup.

Currently we do not implement mid-execution capture. We run capture on
all frames. Including frames before the start frame. We do this to
intercept compiled shaders and programs for easier caching. This could
be changed in the future to also start capture mid-execution. Mid-
execution capture might require using ProgramBinary calls to capture
shader and program data.

Many captures are unimplemented. Several comments indicate missing
functionality. There's a lot we can add as we explore replaying more
complex applications and higher GL versions. We will also need some
kind of state reset functionality so we can run the replay in a loop.

Bug: angleproject:3611
Change-Id: I51841fc1a64e3622c34e49c85ed8919a9a7c0b20
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1689329
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Cody Northrop <cnorthrop@google.com>