Relax OpenZeppelin upgrades plugin validation checks

[cam-schultz]

Why this should be merged

Fixes #648 by allowing constructors and external library calls.

How this works

Adds NatSpec comments to the upgradeable validator-manager contracts to bypass the constructor and external-library-linking validation rules.

How this was tested

Ci

How is this documented

N/A

[iansuvak]

The change LGTM but did we confirm it actually accomplishes the goal?

[cam-schultz]

The change LGTM but did we confirm it actually accomplishes the goal?

I haven't directly. I'm hitting some confusing errors when running a forge script that calls the upgrades plugin. The NatSpec comments should apply to the entire contract , however.

That said, I'd also be fine leaving it to users to pass the relaxation flags to the plugin themselves. In which case, we would just want to document the process and leave the source code alone.