Feature/schema function independent

[salamonpavel]

As part of this pull request, DBSchema has been made an optional constructor parameter of DBFunction. Additionally, the logic for deriving the functionName has been updated.

Separating the concerns of function name derivation between DBSchema and DBFunction is beneficial for a few reasons:

1. Decoupling: By separating these concerns, DBFunction doesn't need to know the details of how the schema name is derived. It just needs to know that it can get a schema name from DBSchema. This decoupling makes the code more modular and easier to change. It also means that changes to how the schema name is derived won't affect the DBFunction class, and vice versa.

2. Consistency: By centralizing the logic for function name derivation in DBFunction, you ensure that the same logic is used consistently across all instances of DBFunction. This can help prevent bugs and inconsistencies that might arise if different parts of the codebase were deriving function names in different ways.

3. Flexibility: The DBFunction class can be used with or without a DBSchema. By separating the concerns of function name derivation, you allow for greater flexibility in how DBFunction instances are created.

4. Code Reusability: The logic for deriving the function name is encapsulated in DBFunction. This means that the same logic can be reused for all DBFunction instances, regardless of whether they have a DBSchema or not.

5. Ease of Testing: With separated concerns, it's easier to write unit tests for each class. You can test the schema name derivation logic in DBSchema independently of the function name derivation logic in DBFunction.

Separating the concerns of function name derivation between DBSchema and DBFunction leads to more modular, consistent, flexible, and testable code.

[github-actions]

JaCoCo code coverage report - scala 2.12.17

File	Coverage [40.92%]	❌
DBSchema.scala	100%	🍏
DBFunction.scala	32.96%	❌

Total Project Coverage	51.95%	🍏

[github-actions]

JaCoCo code coverage report - scala 2.11.12

File	Coverage [49.58%]	❌
DBSchema.scala	100%	🍏
DBFunction.scala	42.26%	❌

Total Project Coverage	51.8%	🍏