Reorganize tensor.basic.py and tensor.math.py.

[ricardoV94]

Description

These two are doing way too much. We should probably split more along the lines of how we listed #821 if not more fine-grained.

• Elemwise (which DimShuffle is not!)
• Reduce: CAReduce + Argmax
• Alloc (or tensor_creation or something): Ops that create tensors (Alloc, AllocEmpty, Diagonal, Arange, ...)

basic and math are just too big and vague. Also the rewrites should be restructured a bit to reflect the changes, although it's sometimes tricky when you are rewriting Elemwise + Reduce or Elemwise + Alloc, Probably we can put it in the non-elemwise, since that's more specific

[ricardoV94]

Also extra_ops is a mess and includes many things that make more sense elsewhere

[poojatalele]

I would like to work on this, kindly assign. @ricardoV94