Impellerc can generate invalid program names from shaders that have files names which are not valid identifiers in the target language #116863
Description
For example, given the shader named "mandelbrot-unrolled", impellerc will attempt to generate a main function named "mandelbrot-unrolled_fragment_main_out" which is an invalid identifier.
Split from #116850
Could not register dynamic stage library: program_source:8:18: error: expected unqualified-id
struct mandelbrot-unrolled_fragment_main_out
We should process that same it is only valid identifiers. I don't think we need to worry about collisions from different shaders, we just need to add a predictable prefix to avoid collisions from imports and flutter specific additions