[DependencyIngection][ParameterBag] Merge array parameters into config #12038 

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #12038 
| License       | MIT
| Doc PR        | no

I added unit tests to cover the possible combinations for `[` and `]` usage, so BC is preserved.
Please tell me if I missed a pattern, so I can add the unit test case and eventually adujst the code to handle it.