Expose hasPrimaryKey method in Table object

[MasterOdin]

This adds a new method to the Table object to allow checking for the existence of a primary key. This mirrors the existing hasForeignKey function on the object.

[MasterOdin]

@dereuromark I guess the ideal way to add a test for this would be to do something like:

public function testHasPrimaryKey() {
    $mock = $this->createMock(AbstractAdapter::class);
    $mock->expects($this->once())->method('hasPrimaryKey')->with('test', 'col', null)->toReturn(true);
    $table = new Table('test', [], $mock);
    $this->assertTrue($table->hasPrimaryKey('col'));
}

The adapters themselves have tests for hasPrimaryKey so probably don't need to replicate that logic here. Thoughts?

[dereuromark]

You could add a type for the 2nd param it seems. Same for return value

[MasterOdin]

I would not want to add type hinting to just one function in this file for fear of overall consistency. Perhaps on a release of 0.13, could do a quick release of 0.14 which just adds type hints where possible across the entire codebase, and then going forward type hints are always used?

Could also land such work in 0.13, but I'd almost at this point just say I'll get back to and land #1962 and then release instead of having it drag out too much longer.

[dereuromark]

Consistency sure is a point.
But this is a new public API method that is added.
And I think the benefits of types in place weigh higher than the consistency argument (from user perspective anyway).
I agree that any 0.13 semantic major release would need to clean up all possible types.