Registration of code points at MP4RA

[cconcolato]

We need to register the following at MP4RA:

• iamf brand
• iamf sample entry

[tdaede]

I will submit the registration for these.

[sunghee-hwang]

Lest we forget, 'iacb' is a temporary candidate.

[sunghee-hwang]

We need to register 'iacb' at MP4RA.

[sunghee-hwang]

@tdaede,
I can't find the IAMF atoms in https://mp4ra.org/registered-types/boxes.
Can you please double-check if "iamf" and "iacb" have been registered at MP4RA?