Factorized requires_tz_support decorator in test utils

Thanks Aymeric Augustin for the suggestion. Refs #21165.
Fixed #21195 -- Clarifed usage of template_name in tutorial part 4.
Fixed #21031 -- Updated schema migrations FAQ.

Thanks ramiro for the report.
Fixed #10733 -- select_related().only() failure

The bug was reported pre 1.1, and somewhere along the way it has been
fixed. So, this is tests only addition.
Fixed #21207 -- Fixed test failure on Oracle: test_cursor_contextmanager

refs #17671
Fixed #21203 -- resolve_columns fields misalignment

In queries using .defer() together with .select_related() the values
and fields arguments didn't align properly for resolve_columns().
Added default value for a BooleanField in test models

Test models introduced for #10733 didn't contain default value for
a BooleanField(). Check command didn't like that -> check tests failed.
Fixed #21147 -- Avoided time.time precision issue with cache backends.

The precision of time.time() is OS specific and it is possible for the
resolution to be low enough to allow reading a cache key previously set
with a timeout of 0.
Fixed #15185 -- Allowed ModelAdmin.list_display_links=None to disable change list links.

Thanks rm_ for the suggestion.
Fixed #21209 -- .po file path comments on Windows.

Literals from source files with Django template language syntax don't
have a '.py' suffix anymore.

Also, the '.\' prefix is preserved to respect GNU gettext behavior on
that platform.

Refs #16903.
Fixed tests breakage from last commit.
Made skipping of symlink-related makemessages test smarter.

os.symlink() is available starting with Windows Vista but can fail at
runtime.
Made test for issue 19552 compatible with Windows.

Take in account platform path separator. Refs #19552.
Fixed #21129 -- Prevented admin filter params modifications from throwing an exception.

Thanks Tuttle for the report.
Fixed #21122 -- Improved clean up of test temp directory on Windows

- Fixed test that didn't close the files it opened
- Caught and handled exception when temp directory cannot be removed
Clarified session replay attack differences with cookie backend.
Changed the doc to use gender-neutral pronouns when possible.
Fixed #10913 -- Documented how related_name affects QuerySet filtering

Thanks neithere for the suggestion.
Initial version of MigrationOptimizer and tests
Fixed #16919 -- Passed user to set_password_form in GET requests.

Thanks Jaime Irurzun for the report and initial patch and
ejucovy for the test.