update BaseActiveRecord

[Bhoft]

Update BaseActiveRecord so that link() and unlink() supports viaRelation on conditions.

Q	A
Is bugfix?	yes
New feature?	no
Breaks BC?	no
Tests pass?	yes/no
Fixed issues	#17174

[yii-bot]

Thank you for putting effort in the improvement of the Yii framework.
We have reviewed your pull request.

In order for the framework and your solution to remain stable in the future, we have a unit test requirement in place. Therefore we can only accept your pull request if it is covered by unit tests.

Could you add these please?

Thanks!

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This is an automated comment, triggered by adding the label pr:request for unit tests.

[Bhoft]

I have realized that the On Condition of the ActiveQuery could also be a String.
My solution only handles the conditions by array.
I am not sure how a "string" condition could be split up into parts to fill the $columns array.
Maybe its enough to throw an error if its an string.
So at least the condition via arrays are handled correctly.

for unlink() something like this would work because it used internally updateAll and deleteAll

if (!empty($viaRelation->where)) {
    $columns = ['and', $columns, $viaRelation->where];
}
if (!empty($viaRelation->on)) {
    $columns = ['and', $columns, $viaRelation->on];
}

but for link() i have no clue how i could guess the preset values for the insert.
If on is an array its not a big deal. But for relations e.g. with an additional where as a string...

But as for link() there is already a possibility to preset the columns of the junktion table both could be linked and unlinked.

[bizley]

Closed in favor of #18564