Enh: Put the DICOM header extracted metadata meta into a Variant Delta Lake data type.

[dmoore247]

Is your feature request related to a problem? Please describe.
Speed the performance of processing the Dicome metadata header

Describe the solution you'd like
Change the data type of the meta column in the object_catalog from STRING to VARIANT.
Adjust readme, pre-requisites according.y

Describe alternatives you've considered
Could keep it as a STRING.

Additional context
The meta field is very complex JSON and may have custom fields in it (which may contain PII, PHI)

[dmoore247]

Variant should be GA in Q4 (Nov-Jan) which could improve tag query performance by 8-9x.