Fixed #22272 -- Fixed regression in DecimalField when using decimal_places=0.

Thanks to trac user merb for the report.
Changed start of week for Australia to Sunday as requested in https://code.djangoproject.com/ticket/21989
Fixed #22001 -- Ensure db_type is respected.

db_parameters should respect an already existing db_type method and
return that as its type string. In particular, this was causing some
fields from gis to not be generated.

Thanks to @bigsassy and @blueyed for their work on the patch.

Also fixed #22260
Merge pull request #2430 from NathanRSmith/ticket_21989

Fixed #21989 - Modified first day of week in AU locale.

Although Australia is a signatory to ISO 8601, there's a lot of evidence to suggest that this is in the same category as "officially, the USA uses metric". See the ticket for supporting details.
Fixed #22184 -- Allowed template_tests.tests to be run isolated
Remove u prefixes, skip test unless spatial db.

Refs #22001, d22b291890c1736a40c0ad97448c7318df2eebb2
Fixed #22242 -- Documented common cookie size limit.
Fixed #21991 -- Added warning regarding tests failure if locales not installed.

Thanks reidrac for the report.
Fixed #21860 -- Added to_field_name to ModelChoiceField docs.

Thanks Keryn Knight for the suggestion.
Fixed #22006 -- Documented how to write a login_required mixin for CBVs.

Thanks django at patjack.co.uk for the suggestion and mockforest
for the draft patch.
Fixed #21179 -- Added a StreamingHttpResponse example for CSV files.

Thanks charettes for the suggestion.
Amended login required mixin documentation to honor **initkwargs.