Adding a switch for normalising types at elaboration time

[kmemarian]

This switch replaces type aliases (e.g. size_t, uintptr_t) with their implementation-defined choice during the elaboration to Core.

This commit enables the switch in the frontend of CN.

This should address some issues from #678, #236, #272.

@cp526 for #678 CN now gives a "Missing resource for reading" error on variables with the alias type.

[kmemarian]

@cp526 the CI failures are the same

[cp526]

Thanks very much @kmemarian , that looks great!

The missing step to fix those CI failures is probably for CN to apply the same normalisation of C-types in certain places, so that where C-type equality is required (e.g. the resource inference), it uses equality post normalisation.