Indexing support for blob or colder storage tiers. #1210

diskann index type is designed and tested for in-memory and local SSD tiers.
We want to extend indexing support to blob and other colder tiers. This requires:

• exploration of suitability of diskann for other tiers
• additional index types if necessary
• distance kernels for columnar formats
• index serialization for OSS table/file formats.
• perf testing on ADLS, HDD, remote disks etc.