TIFF manifest store embedding not conformant with C2PA 1.4+

[darrellkindred]

In a TIFF asset, according to the spec (https://c2pa.org/specifications/specifications/2.1/specs/C2PA_Specification.html#_embedding_manifests_into_tiff_based_assets):

the C2PA Manifest Store shall be the only box present in the last IFD, the IFD immediately preceding the end of the file.

However, it looks to me like the manifest store is being inserted in an existing IFD instead of in a new one.

[darrellkindred]

Ah, just noticed this note in the spec:

Previous versions of this specification required the use of IFD 0, but it was recognized that doing so restricted its use in TIFF-based RAW formats.

So it looks like the embedding implementation follows C2PA 1.3 (the new location has been required since 1.4).