gh-73613: Support Base32 and Base64 without padding (GH-147974)

Add the padded parameter in functions related to Base32 and Base64 codecs
in the binascii and base64 modules.  In the encoding functions it controls
whether the pad character can be added in the output, in the decoding
functions it controls whether padding is required in input.

Padding of input no longer required in base64.urlsafe_b64decode() by default.