[Python][Docs] Update/rearrange Data Types section and add FixedShapeTensorType

[AlenkaF]

Describe the enhancement requested

The Data Types and In-Memory Data Model section in our documentation is already quite long and includes a lot of things. With the fixed shape tensor canonical extension type (and RunEndEncodedType) added to pyarrow, this section could be rearranged and should include newly added Data Types also.

Component(s)

Documentation