feat: [MariaDB] Support RETURNING clause

[devgor88]

Description

Summary of the change: Returning clause was implemented for MariaDB

Detailed description:

• What: Returning clause was implemented for MariaDB.
• Why: Returning clause is widely used, but MariaDB support was not included when RETURNING clause was introduced in either feat: EXPOSED-355 Support INSERT...RETURNING statement #2060 or feat: EXPOSED-357 Support DELETE...RETURNING statement #2061.
• How: FunctionProvider.returning(...) was overridden in MariaDBFunctionProvider. Some tests were fixed and MariaDB is excluded from tests for updateReturning() because UPDATE ... RETURNING is not yet supported by the database (open issue MDEV-5092).

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Type of Change

Please mark the relevant options with an "X":

• Bug fix
• New feature
• Documentation update

Updates/remove existing public API methods:

• Is breaking change

Affected databases:

• MariaDB
• Mysql5
• Mysql8
• Oracle
• Postgres
• SqlServer
• H2
• SQLite

Checklist

• Unit tests are in place
• The build is green (including the Detekt check)
• All public methods affected by my PR has up to date API docs
• Documentation for my change is up to date

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Related Issues

[bog-walk]

Thanks very much for opening this PR @devgor88 !

Please check the comments regarding the tests and please also update the existing documentation, specifically this docs file.
In that file, please add MariaDB to the "Supported on" section in the relevant <tldr> element (line 406). Then we'd need to add a small note about the update restriction, so please also edit the following <p> to clarify the support:

<p>Some databases allow the return of additional data every time a row is either inserted, updated, or deleted.
    Please note that MariaDB only allows the return of this data for insertions and deletions.
    This can be accomplished by using one of the following functions:
</p>

If you need any further clarification or help with these requested changes, don't hesitate to let me know. Thanks in advance!

[devgor88]

Thank you for reviewing this PR. I'm glad to be a one of contributors of this great library. I've done everything you asked for. Hope I haven't broken docs file as I'm not fully understand its format.

[bog-walk]

😄 Thanks again @devgor88 & for your support of the library! Don't hesitate to contribute again or to open a discussion in YouTrack with any ideas about how our MariaDB support could be improved.

By the way, no worries about the docs, they're not broken. If you ever want to contribute more to the documentation in the future, the Writerside plugin could be helpful as it offers a live preview in the IDE for any changes.

[e5l]

Nice work, lgtm