Doc-value fields now return a value that is based on the mappings rather than
the script implementation by default.
This deprecates the special `use_field_mapping` docvalue format which was added
in #29639 only to ease the transition to 7.x and it is not necessary anymore in
7.0.
Make SQL aware of missing and/or unmapped fields treating them as NULL
Make _all_ functions and operators null-safe aware, including when used
in filtering or sorting contexts
Add missing and null-safe doc value extractor
Modify dataset to have null fields spread around (in groups of 10)
Enforce missing last and unmapped_type inside sorting
Consolidate Predicate templating and declaration
Add support for Like/RLike in scripting
Generalize NULLS LAST/FIRST
Introduce early schema declaration for CSV spec tests: to keep the doc
snippets in place (introduce schema:: prefix for declaration)
upfront.
Fix#32079
James Rodewig
Costin Leau
Adrien Grand
Marios Trivyzas
Jason Tedor
Lisa Cawley