Internalize setRoyaltyPolicy call into LicenseRegistry

[jdubpark]

Currently, the Policy Framework Managers (PFMs) are in charge of calling setRoyaltyPolicy (RoyaltyModule) on license linking to parents, triggered by verifyLink in LicenseRegistry's linkIpToParents. The Royalty Module restricts the caller to the IPAccount owner OR registered PFMs.

This opens up a huge vulnerability issue. Any PFMs can set royalty plicy on any IPAccounts. Since setting a royalty policy is an irreversible, one-time action per IPAccount, a malicious PFM can set royalty policy on random IPAccounts, thus preventing actual royalty policy registrations.

A proposed solution is whitelisting PFMs. Even with this solution, any whitelisted PFM can maliciously or accidentally call setRoyaltyPolicy on any IPAccounts.

A better, working solution is to call setRoyaltyPolicy from the LicenseRegistry, after verifying links and checking the compatibility of parent licenses in linkIpToParents.

[Ramarti]

LGTM