key rotation without manifest update

[lpiron]

CPIX has been written before this possibility, described in DASH-IF IOP, was introduced (section 9.3 of https://dashif.org/docs/IOP-Guidelines/DASH-IF-IOP-Part6-v5.0.0.pdf).

• In CPIX, it is written, Under the DRMSystem element description, that if there is no key hierarchy then the PSSH goes under the moov box, which is not what shall be done for key rotation without manifest update (it goes under the moof).
• A key server does not generate the same ContentProtectionData element when there is key rotation without manifest update and there is no way for signaling this (no ContentProtection child elements such as PSSH elements).