Rename functions

I feel like some functions names no longer fit their purpose and it would be better to rename it.

- `make_tracer`: doesn't fit because we are not _creating a tracer_ but it _traces_ through the fields of a type and returns a new type with the Reactant-managed arrays changed in some way.
- Proposals: `linearize`? `trace`?
- `make_mlir_fn`: This is a very important function because it actually performs the partial evaluation of the code inside a MLIR context and returns the emitted MLIR code. `make_mlir_fn` fits partially IMO.
- Proposals: `partial_evaluate`? `interpret`? also `trace`?