Add support for SQLite shorthand form in foreign key constraints

[phansys]

Q	A
Type	feature
Fixed issues	#5941

Summary

Introspect the referenced table in order to get the foreign column.

Closes #5941.

ToDo

• Check support for composite columns.

[greg0ire]

What if the primary key of the foreign table is composite? What should happen then?

[phansys]

I didn't know SQLite was supporting single column and composite (multiple column) primary keys.
To keep it simple, my first though would be to add support only for single column keys in this PR and throw an exception if it is composite, allowing the further development to implement the remaining part.
But let me confirm if I can give it a try tomorrow before giving up so quickly 😄

[derrabus]

As far as I understand, DBAL would not emit the kind of shorthand syntax that you use in that functional test of yours. It would instead emit a more verbose version that explicitly references the foreign column. So the problem you're solving here applies to databases that have not been created by DBAL.

My question: If I encounter such a table, would DBAL try to migrate it to the more verbose version or leave it as it is? Can we cover the answer to that question with a test? 🙃