Add inline functions

[Balint-R]

We should add an @inline decorator that converts a PyDSL function into an inline function. Such an inline function should behave semantically very similarly to a normal function, but its MLIR should be inlined. This means type hints are not necessary. The inline function should probably not be able to access variables from the function that calls it, will have to check how the existing scope mechanism in PyDSL works to see if this is easy to support.

I will implement this feature very soon, since we want it for linalg.reduce.