User controllable and automatic constant memory placement

[PMQ9]

Implement some ideas for this issue: #218

Add explicit memory placement

Add methods allowing users to explicitly place:

• static(s)
• crate(s)
• specific static(s) in a crate

in constant or global memory.

Add constant memory space overspill automatic handling

use_constant_memory_space = false by default

• All statics will go to global memory
• User can use the method above to explicitly place specific static(s) or crate(s) to constant memory
• No auto-packing, no overflow warnings (user is responsible for ensuring what they want to place in constant memory actually fits)

if use_constant_memory_space = true

• All eligible statics (immutable, freeze) automatically try to go to constant memory
• Calculates the total size of all the statics that the user explicitly wants to place in constant memory, reserve some space for that
  • If the reserve space is larger than constant memory, throw a warning
• The remaining statics: auto-packing kicks in, first-come-first-served, overflow spills to global with warnings
• User can specify static(s) or crate(s) that they want to put in global, these will be exclude from automatic packing