ctypes: Add docstrings for `ctypes.pointer` and `ctypes.POINTER`

[tomasr8]

ctypes.pointer and ctypes.POINTER from the ctypes module are currently lacking docstrings. I suggest we add those.
Luckily, these functions are already documented in the docs so it should just be a matter of reusing the description from the docs.
It has also been recommended that we convert both functions to Argument Clinic when adding the docstrings.

Linked PRs

• gh-107659: ctypes: Add docstrings for ctypes.pointer and ctypes.POINTER #107660
• gh-107659: Add docstring for ctypes.POINTER & ctypes.ARRAY #107739
• gh-107659: Improve wording of the description of ctypes.pointer and ctypes.POINTER #107769
• [3.12] gh-107659: Improve wording of the description of ctypes.pointer and ctypes.POINTER (GH-107769) #108163
• [3.11] gh-107659: Improve wording of the description of ctypes.pointer and ctypes.POINTER (GH-107769) #108164