Context

Storing contract code costs gas - just like storing anything else on Ethereum.

Related #5119

Thomas' comment

This MR needs additional testing, but is otherwise good.

Hantang's comment

thomas implem is not correct we should pay 200 gas for every byte in storage of code, cf page 27 of yellow paper

There are still some uncovered gas costs around contract creation. MR !10349 (merged) adds the remaining parts.

Manually testing the MR

Existing tests of contract creation have been updated.

Specific tests for contract creation gas cost added.

Document the interface of any function added or modified (see the coding guidelines)
Document any change to the user interface, including configuration parameters (see node configuration)
Provide automatic testing (see the testing guide).
For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
Select suitable reviewers using the Reviewers field below.
Select as Assignee the next person who should take action on that MR