Forward compatibility layer for `AbstractPlatform::getColumnDeclarationListSQL()`

[derrabus]

The ORM makes use of the AbstractPlatform::getColumnDeclarationListSQL() method. This method requires a list of column definitions. The structure of that array has been changed in 5.0:

4.3.x:

dbal/src/Schema/Column.php

Lines 23 to 24 in 7669f13

	* @phpstan-type ColumnProperties = array{
	* name: string,

5.0.x:

dbal/src/Schema/Column.php

Lines 22 to 23 in 711dcec

	* @phpstan-type ColumnProperties = array{
	* name: UnqualifiedName,

While the name key is supposed to be a string in 4.3.x, it has to be an UnqualifiedName object in 5.0. I need to be able to write code that is compatible with both versions and while the UnqualifiedName class is already available in 4.3, I cannot use it in this structure yet. Also, there's no deprecation that indicates that the input type will change in a future release.

Should we allow the usage of UnqualifiedNames in 4.x already and trigger a deprecation if we find a string?