feat: delegate call test

[bajpai244]

Pull Request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build-related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

The current test doesn't test the behaviour delegate call properly.

Resolves: #550

What is the new behavior?

• The bytecode which is executed does SSTORE
• SSTORE of value 0x42 is done at key 0x42
• The existence of value is checked in the storage in the contract which made the delegate call
• This makes sure that opcode is properly being tested.

Does this introduce a breaking change?

• [ ] Yes
• No

[enitrat]

lgtm