feat: [v0.8-develop, experimental]: remove plugin call restriction [3/N]

[adamegyed]

Motivation

#52 identified an issue, where if a validation plugin defined any execution functions, it could not be installed multiple times. This is a goal we're working towards with composable validation, so we need a way to address the issue.

A simple candidate change to address this is to remove the call restriction on plugins, and to handle the logic of guarded functions like transferOwnership through the execute/executeBatch workflows.

Solution

Remove the restriction on _exec to only call non-plugin contracts.

Remove the installation of execution functions owner() and transferOwnership(...) from SingleOwnerPlugin. We should eventually provide this as a non-mandatory option during install, but that is not addressed here.

Future work

This PR does not address the security ramifications of this - it breaks the segmentation of validation functions provided by the 1:1 association of selectors and validation. We will need to implement some ability to filter calls based on the type of validation used in the future.

[jaypaik]

I generally like this direction. Could you leave a TODO somewhere appropriate to track validation-execution association?

[huaweigu]

Removing the installation of execution functions on plugins is an interesting idea. Would it be accurate to say this approach essentially recommends native exec functions such as execute/executeBatch, and simplifies the enforcement of global validation?

[adamegyed]

Yes, I think that's accurate @huaweigu. It simplifies the enforcement, but we may need to provide ways to lock it down more in the future. It could be necessary for cases when a plugin wants to add protections to specific functions, like transferring ownership.