Make execution functions payable in the standard

[filmakarov]

Idea

There are use cases, that require passing value from the Executor to the SA along with executeFromExecutor and executeBatchFromExecutor calls.
For example, a module that enables perp trading features with the MSA.
In such a use case, to keep the interface consistent between perp DEX and the module and avoid extra gas overhead, the above mentioned methods should be payable.

They are currently payable in the reference implementation.

I propose marking them (along with other execution methods) in the ERC description as well.

[zeroknots]

I think this is a pretty good idea. we should do this if there is no vetos :D