feat: implement 0x52 - MSTORE Opcode

[Quentash]

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?

Resolves: #243 and #289

What is the new behavior?

Does this introduce a breaking change?

• Yes
• No

[enitrat]

It would be nice to add a tests that loads the entire memory and verifies the state of it.

For example when you do

    ctx.stack.push(0xFF00);
    ctx.stack.push(0x01);

Then verifying that the memory is 64 bytes long, that the first word is 0xff and the second word is 0.

You should also add two cases where we have:

• no offset
• 32-bytes offset

[Quentash]

Corrected "succeed" into "succeeded".
Used pop_n(2) instea of 2 pop().
Added a test case with offset 0.
Added a test case with offset 32.
Added memory length verification into tests.
Used integer::BoundedInt for max value.

[ClementWalter]

thx, there are too much test for this! in terms of unit testing, when writing tests for exec_{} we mainly need to test that we popped enough arguments, and that we pass them correctly to the underlying function implementing the logic (if the logic is in another funcion, as it is the case here).

[Quentash]

Removed many unnecessary tests.
Reverted back to single pop.
Replaced "only_Fs" by "max_uint256".
Added to self to-do list to read more about english past participle.

[enitrat]

lgtm