[1.7.x] Fixed #22801 -- Added 'www.' to diveintopython.net links

Backport of f97c53c098 from master
[1.7.x] Fixed #22680 --  I/O operation on closed file.

This patch is two-fold; first it ensure that Django does close everything in
request.FILES at the end of the request and secondly the storage system should
no longer close any files during save, it's up to the caller to handle that --
or let Django close the files at the end of the request.

Backport of e2efc8965edf684aaf48621680ef54b84e116576 from master.
[1.7.x] Created a new tests folder (`model_options`).

And moved `tablespaces` option tests to it.
The new folder can be used to test models/options, like the new option
added in refs #22778.

Backport of 5a3ae7e260 from master
[1.7.x] Fixed #22653 -- Added some database feature flags to tests.

Thanks Rahul Priyadarshi.

Backport of 99f5ea9cc8 from master
[1.7.x] Fixed #22487: Separated schema migration from data migration in test

The data migration failed on Oracle, killing the entire test suite.

Thanks timo for reporting the Oracle breakage,
and andrewgodwin for suggesting the solution.

Backport of 64d94cf from master
[1.7.x] Added link to data migrations in initial data deprecation note

Backport of 4123f55c33 from master
[1.7.x] Fixed typo in docs/ref/forms/validation.txt.

Backport of c307383ec9 from master
[1.7.x] Fixed #22813 -- Updated Pillow URL in documentation

Backport of dfa3505ff1 from master.
[1.7.x] Fixed #22818 -- Clarified you need to cd into the Django clone.

Thanks Josh Parris.

Backport of bcc3d2b978 from master
[1.7.x] Fixed test failures due to refs #20420.

cfcca7ccce3dc527d16757ff6dc978e50c4a2e61 renamed connection.queries
to queries_log and this wasn't backported to stable/1.7.x.
[1.7.x] Fixed #22823 (and partly #22563) - FKs from unmigrated apps breaking state.

Thanks to bendavis78 for the test and diagnostic work.
[1.7.x] Fixed #22811 -- Allowed setting both the old and new TEST database settings.

An ImproperlyConfigured exception will be raised they mismatch.

Backport of 1c58cabad7 and a2cd0e12c9 from master
[1.7.x] Fixed a staticfiles test on Windows.

Backport of 9980f67154 from master
[1.7.x] Fix test breakage from previous state fix
[1.7.x] Made the vendored NamedTemporaryFile work as a context manager. Refs #22680.

This fixes a regression on Windows introduced by b7de5f5.

Thanks Tim Graham for the report and review.

Backport of 6e8d614acd from master
[1.7.x] Fixed #22349 -- Added a note clarifying `RawQuerySet` has no `__len__`.

Thanks cdestigter for the report.

Backport of 2d425116e2 from master
[1.7.x] Fixed #22477 -- Removed contrib middleware from the global settings defaults.

Also added a compatibility check for changed middleware defaults.