Generate missing config when asadmin set is called (2nd attempt)

[OndroMih]

Fixes #24158. Automatically creates missing config nodes in the set command, if they aren't present in domain.xml.

Added tests to cover multiple scenarios:

• setting an attribute directly (this test was already present)
• setting an attribute through an alias (a different dotted name leading to the same config node)
• seting a custom property a=b
• setting an attribute on a node which isn't in the current configuration and which will be created before setting the attribute (this is the new feature implemented)

This is a fix of #24160, which was reverted by #24170 to pass the tests.