More convenience build methods for SPIR-V ops.

Add some convenience build methods to SPIR-V ops and update the
lowering to use these methods where possible.

For SPIRV::CompositeExtractOp move the method to deduce type of
element based on base and indices into a convenience function. Some
additional functionality needed to handle differences between parsing
and verification methods.

PiperOrigin-RevId: 284794404