`mmap` objects does not support __contains__ operation with ints (unlike bytearray!)

Bug report

Bug description:

The following code

import mmap

with open('test.dat', 'wb') as f:
    f.write(b'A')

with open('test.dat', 'rb') as f:
   mm = mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ)
   print(65 in memoryview(mm))
   print(65 in bytearray(mm))
   print(65 in mm)
   mm.close()

prints

True
True
False

this even though mmap documentation claims that mmap works exactly like bytearray.

There is also discrepancy in the __iter__ implementation, but for that there is a workaround of using a memoryview object and that would be possibly backwards-incompatible change.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

まず、Linux 上で CPython main を使って、issue にある mmap、memoryview、bytearray の再現を実行します。mmap オブジェクトの包含動作を追跡し、整数のメンバーシップに対するテストカバレッジを追加または更新します。完了の条件は、mmap が bytearray の文書化された動作に一致し、指摘された反復動作にリグレッションを起こさないことです。