deprecate add_transform

We favour the JIT interface to be used as
`jfoo = thunder.jit(foo, transforms=[A(), B(), C()])`
rather than
`jfoo = thunder.jit(foo) ; jfoo = add_transform(A()); jfoo = add_transform(B()); jfoo = add_transform(C()); `.

In the second pattern, A is applied 3x and B 2x. Also it is unclear what should happen to other parts of compile data.

Thus I propose to remove add_transform.
We do use it in some of our tests, but it should not be too user-facing.

Start by searching the repository for add_transform and the tests that use it, then compare those usages with the thunder.jit transforms interface described in the issue. Done means add_transform is removed as a user-facing path and the affected tests use the preferred interface without leaving broken references.

Written by the indexing model from the issue text.