Prefix Lift and Lower trait methods with memory_

[fitzgen]

This is to distinguish them from the GC versions that will be added in follow up commits.

No functional changes here, just renaming.

[alexcrichton]

To motivate a bit of a bikeshed: these sorts of changes tend to have a very high sticking power where they stick around for a very long time so I'd ideally like to handle things in one fell swoop instead of going through multiple renames. To bikeshed: memory_lift and memory_load are IMO deceptively subtle in how they're different as "lift from memory" is something I would reasonably say should be synonymous with a load from memory. Given that I'd prefer to find different names that are more nuanced than just putting memory_* in front of what we currently have.

One observation as well is that I think there's probably not going to be a gc_load or a gc_store. Current design has lifting/lowering of GC values being mostly like the "flat" lifting/lowering of linear memory values. I realize the struct/array cases are a bit different but I think what we'll probably do is pass a parameter through which differentiates the local/struct/array source/destinations of values.

Naming-wise WDYT about {lift,lower}_{linear,gc} and otherwise leaving load and store as-is? (or maybe {load,store}_linear)

[fitzgen]

For the GC methods I currently have:

• Lift::gc_lift_val for doing GC lifting from a value
• Lift::gc_lift_storage for doing GC lifting from a storage type (i.e. a struct field or array element)
• Lower::gc_lower_val for doing GC lowering into a value
• Lower::gc_lower_storage for doing GC lowering into a storage type

[fitzgen]

How about

• Lift::lift_from_flat_linear
• Lift::lift_from_memory_linear
• Lift::lift_from_val_gc
• Lift::lift_from_storage_gc
• Lower::lower_to_flat_linear
• Lower::lower_to_memory_linear
• Lower::lower_to_val_gc
• Lower::lower_to_storage_gc

?

[alexcrichton]

That sounds good to me 👍