Fixed #23298 -- Made makemessages actually ignore specified dirs on Windows.

This was detected by two failures in the i18n.test_extraction of our
test suite.

Refs #20422, refs #22336
Fixed #23263 -- Added sqlmigrate to migration topic guide.
Fixed #23309 -- Fixed call_command to parse args correctly
Merge pull request #3075 from ramiro/makemessages-ignore-windows

Fixed #23298 -- Made makemessages actually ignore specified dirs on Wind...
Fixed #14638 -- Clarified model Field.to_python() docs.

Thanks Anubhav Joshi for the patch.
Fixed #23303 -- Added BEGIN and COMMIT statements to the output of sqlmigrate.
Fixed #23136 -- Added a message when sqlclear does nothing
Fixed flake8 warning.
Removed test, duplicate of admin_scripts.CommandTypes tests
Fixed #22171 -- Improved sanitize_separators cleverness

Thanks Klaas van Schelven for the report and Tim Graham for the
review.
Fixed some doc errors that caused syntax highlighting to fail.
Fixed #5726 -- Documented that inspectdb doesn't detect defaults.
Fixed #4991 -- Emphasized XSS ramifications of help_text not being escaped.
Fixed #23282 -- Corrected inheritance and reverse relations example.

Thanks knowledgepoint-devs for the report and claudep for review.
Fixed #17272 -- Documented that non-editable fields are skipped during model validation.

Thanks mitar for the report.
Fixed #23314 -- Tempered recommendation of storing profile data on custom user.

Thanks gavinwahl for the report.
Replaced HAS_SPATIAL_DB by testing database feature

Refs #22632. This should be the base for using more database
features to exclude specific backends in GIS tests.
Thanks Tim Graham for the review.
Fixed broken tests on Oracle after 5853c87a458f62ebd62d7809168355610de2570c.

Oracle doesn't have a `BEGIN` statement so the test would
fail.

Refs #23303
Fixed #21801 -- Documented SingleObjectMixin.get_context_data() requires the object attribute.
Removed unused imports.