Makes some white-space differences in most output, plus a few cases
where more could have been put out but was cut short by the previous
fix-sized buffer.
Sets highp defaults for the appropriate types, for all stages,
and turns on precision qualifiers for non-ES shaders. Required
fixing some qualifier orders for desktop built-in declarations
for pre-420 shaders.
Note: This required adding a new test mode to see the AST for vulkan tests.
This also required reworking some deeper parts of type creation, regarding
when storage qualification and constness is deduced bottom-up or dictated
top-down.
