[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

[thisisnic]

This issue has been marked as stale because it has had no activity in the past 2 years. Please remove the stale label or comment below, or this issue will be closed in 14 days.

[tadeja]

A fresh request to have the section Canonical Extension Types moved out of 'Extending PyArrow' document page has just come up in #48727 (comment) where subsection UUID is getting added.

@rok , @AlenkaF could you check about removing stale label here and whether this item could be added to #46601 for visibility?