Support asset field in BaseTransaction - Closes #3697

[MaciejBaj]

What was the problem?

Each time while defining a transaction extending BasicTransaction there is a need for implementing the complex constructor supporting the asset field and assetToJSON function which is the same for all transaction types.

How did I fix it?

• assign asset field in the constructor of BasicTransaction
• implement default assetToJSON method in BasicTransaction

How to test it?

Review checklist

• The PR resolves Support asset field in BaseTransaction #3697
• All new code is covered with unit tests
• All new code was formatted with Prettier
• Linting passes
• Tests pass
• Commit messages follow the commit guidelines
• Documentation has been added/updated

[MaciejBaj]

I will remove the overridden implementation from the default transaction types. The implementation is the same. Setting to in progress

[MaciejBaj]

@shuse2 @SargeKhan I would prefer to keep the simplest version accepting the risk of possible confusion in the case of non-deterministic order of keys in assets. The proper research is currently ongoing. I added the relevant FixMe to the assetToBytes function.

[shuse2]

For 2.1, we will go with this temporal solution, but it should be mentioned in the documentation that we strongly recommend to override this assetToBytes @MaciejBaj