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for function of AddRenderEntityWithFiltersToCurrentPass,

refer to the following commit:
    72cfdc7("Add foundation for uber SDF shader and Contents (flutter#183864)")

Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>

issues: flutter#183036

This implements the basic foundation for the UberSDF work. There are
improvements we will want to make on it but everything implemented here
is behind flags in `main` and has golden tests.

Right now it is using a stand-in implementation of the sdf renderer that
doesn't incorporate all the work we've done for the circle sdf renderer.

It also doesn't render gradients yet in this pr, that is happening in
flutter#184090

Design doc:
-
https://docs.google.com/document/d/166uRQBoKfraIibNKYxrewzVcmflqIWde80uB7L5bJSs/edit?tab=t.0


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