Cakephp: Add support for PostgreSQL FROM clause in UPDATE statements

[thinkingmedia]

This is a (multiple allowed):

• [ ] bug
• [x] enhancement

• [ ] feature-discussion (RFC)

• CakePHP Version: 3.4.0

• Platform and Target: PostgreSQL 9.5

What you did

PostgreSQL supports the updating of table_a from table_b as part of the syntax of an UPDATE statement using the FROM clause.

What happened

FROM clause is ignored.

What you expected to happen

Support for the FROM clause in the UPDATE SQL when using PostgreSQL.

Please note: I had already added support in #9730 but I want to now separate into a different pull request for testing reasons.

[lorenzo]

I would like this, but also for MySQL... I think SQL server also supports it

[github-actions[bot]]

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