Systematically synthesize spans

[workingjubilee]

Like #1667 but with a checklist instead. Doing this correctly can have a significant impact on diagnostics, for instance: 2c1d388

• pgrx-macros

  • lib.rs
  • rewriter.rs
  • operators.rs

• pgrx-sql-entity-graph

  • aggregate/aggregate_type.rs
  • aggregate/mod.rs
  • composite_type.rs
  • enrich.rs
  • extension_sql/entity.rs
  • extension_sql/mod.rs
  • extern_args.rs
  • finfo.rs
  • lifetimes.rs
  • pg_extern/argument.rs
  • pg_extern/attribute.rs
  • pg_extern/cast.rs
  • pg_extern/entity/argument.rs
  • pg_extern/entity/cast.rs
  • pg_extern/entity/mod.rs
  • pg_extern/entity/operator.rs
  • pg_extern/mod.rs
  • pg_extern/operator.rs
  • pg_extern/returning.rs
  • pg_extern/search_path.rs
  • pg_trigger/mod.rs
  • positioning_ref.rs
  • postgres_enum/entity.rs
  • postgres_enum/mod.rs
  • postgres_hash/entity.rs
  • postgres_hash/mod.rs
  • postgres_ord/entity.rs
  • postgres_ord/mod.rs
  • postgres_type/entity.rs
  • postgres_type/mod.rs
  • schema/entity.rs
  • schema/mod.rs
  • to_sql/mod.rs
  • used_type.rs