Fixed #29725 -- Removed unnecessary join in QuerySet.count() and exists() on a many-to-many relation.

The HTML characters are unused because urlize is meant to be applied to
plain text and these characters aren't properly detected (refs #29826).
Angle brackets and quotes are present in word_split_re and therefore
won't be used in WRAPPING_PUNCTUATION.

django.utils.http.urlsafe_base64_encode() now returns a string, not a
bytestring. Since URLs are represented as strings,
urlsafe_base64_encode() should return a string. All uses immediately
decoded the bytestring to a string anyway.

As the inverse operation, urlsafe_base64_decode() accepts a string.

When using include() without namespaces of some urlpatterns that
have an include() with namespace, the converters of the parent
include() weren't being used to convert the arguments of reverse().

Support for passing bytestrings to the database API was removed in
301de774.

contrib.sites is included in INSTALLED_APPS by SitemapTestsBase.

SessionBase.decode() is the inverse operation to SessionBase.encode().
As SessionBase.encode() always returns a string, SessionBase.decode()
should always be passed a string argument. Fixed the file backend, which
was the only backend still passing a bytestring.

The mysqlclient cursor attribute `_last_executed` is always stored as
bytes. Decode it.

TextField values are already type str. No need to decode.

Support for bytestring templates was removed in
3a148f95.

The old implementation considered objects initialized with an equivalent
signature different if some arguments were provided positionally instead of
as keyword arguments.

Refs #11964, #26167.