Add code comment for proxy & upgradeability

### Describe the desired feature

Since 0.8.3 we support custom code comment (ex: `@custom:security non-reentrant`), we can add the support for things like:
- `@custom:security isProxy`
- `@custom:security isUpgradeable`
- `@custom:version name:`
for the contract definition.

This will allow to leverage some of the detectors from `slither-check-upgradeability` automatically (without having to specify manually what contracts are upgradeable, the version etc...)