This pr drops support the 7.x Nest client (unsupported EOY see elastic/elasticsearch-net#8014 (comment)) and upgrading to the new Elastic.Clients.Elasticsearch client.

Blocking Issues (WIP)

• Missing Aggregation LocalMetdata (8.15.6 - Bring back Aggregation LocalMetadata elastic/elasticsearch-net#8334)
• API Feedback (8.15.6 - General API Feedback while upgrading from NEST. elastic/elasticsearch-net#8339)
  • Aggregations internalized / no base types
  • Aggregation descriptor has fluent dictionaries instead of being more open.
  • Sub Aggregations are hard to define now
  • IProperty fields
• SortOptions AdditionalPropertyName internalized (8.15.6 - Make public SortOptions.AdditionalPropertyName elastic/elasticsearch-net#8335)
• IPropertyWithClrOrigin Replacement (8.15.6 - IPropertyWithClrOrigin replacements? elastic/elasticsearch-net#8337)
• IProperty.Name (8.15.6 - Bring Back IProperty.Name elastic/elasticsearch-net#8336)
• ExtendedBoundsDate doesn't have helper for converting min max from date time (8.15.6 - ExtendedBounds -> ExtendedBoundsDate needs implicit convertors for anchored DateTime elastic/elasticsearch-net#8338)
• AutoMap ([FEATURE] Support AutoMap to allow creation of mappings using type inference elastic/elasticsearch-net#6610)
• QueryDescriptor Operand/Operator (!, ||, &&) overloads (Logical operations between QueryDescriptor objects are not allowed elastic/elasticsearch-net#8002)
• AggregationDescriptor / QueryDescriptor assignment (Consolidate usage of FluentDescriptorDictionary elastic/elasticsearch-net#8349)
• Sorting Feedback 8.15.6 - Sorting Feedback elastic/elasticsearch-net#8350