Rollup merge of #107248 - erikdesjardins:addrspace, r=oli-obk

abi: add AddressSpace field to Primitive::Pointer

...and remove it from `PointeeInfo`, which isn't meant for this.

There are still various places (marked with FIXMEs) that assume all pointers
have the same size and alignment. Fixing this requires parsing non-default
address spaces in the data layout string (and various other changes),
which will be done in a followup.
(That is, if it's actually worth it to support multiple different pointer sizes.
There is a lot of code that would be affected by that.)

Fixes #106367

r? ``@oli-obk``
cc ``@Patryk27``