Allows to pass config name to search class configuration

[fullonic]

Description

Updates search-related functions and the SearchCriterion object to receive a new configuration parameter: config_name. By default, we use the PostgreSQL default text search config, pg_catalog.simple.

Motivation and Context

When using PostgreSQL search, the user might need to change the default configuration. This PR makes it possible by allowing the user to specify which config he/she wants to use. For example, using the PostgreSQL extension unaccent, we can now query as:

await City.filter(name__search=ToTsQuery("paris", "public.unaccent"))

Tortoise will generate the below SQL query

'SELECT "id", "name" FROM "cities" WHERE TO_TSVECTOR(\'public.unaccent\',"name") @@ TO_TSQUERY(\'public.unaccent\',\'paris\')'

Because of the current implementation of the __search filter, inside the SearchCriterion.__init__, we extract the config_name from the function in use, in the above example ToTsQuery, to pass it to the ToTsVector function.

How Has This Been Tested?

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added the changelog accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[coveralls]

Pull Request Test Coverage Report for Build 9398386413

Details

• 10 of 11 (90.91%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall first build on feature/allow-pass-dictonary-to-search at 87.856%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
tortoise/contrib/postgres/functions.py	6	7	85.71%

Totals
Change from base Build 9398213175:	87.9%
Covered Lines:	5780
Relevant Lines:	6481

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💛 - Coveralls

[fullonic]

Superseeded by #4