MLBEDSW-6314 Static optimisation for quantise OP

*Quantise op becomes constant if input is known at compile time
*Quantised values calculated if input of op is const and float
*Const inputs to quant op that are int are requantized

Change-Id: Ic94a72a392af709fe6a640d7dacbb5dc2334f16f
Signed-off-by: Ayaan Masood <Ayaan.Masood@arm.com>