Proximity field plugin options have no config schema

Problem/Motivation

The Views field plugin geofield_proximity_field defines three options in GeofieldProximityField::defineOptions(): units, source and source_configuration. Its config schema, views.field.geofield_proximity_field, extends views.field.numeric and adds none of them.

So any view that uses the proximity field fails strict config schema validation. Every kernel test in a module that ships such a view hits this, because KernelTestBase checks schema strictly by default. Config Inspector reports the same errors, and the values are saved without type casting.

The proximity sort, views.sort.geofield_proximity_sort, and the proximity filter, views.filter.geofield_proximity_filter, already declare these keys. The field plugin is the one that was missed.

Present on 8.x-1.67 and on 10.3.x at 41e839fe.

Steps to reproduce

1. Create a view of an entity with a Geofield, and add the "Geofield Proximity Field" field.
2. Export the view and install it from a module's config/install or config/optional in a kernel test, or inspect it with Config Inspector.
3. Schema validation fails with:
   

   views.view.example:display.default.display_options.fields.field_geo_proximity.units missing schema
   views.view.example:display.default.display_options.fields.field_geo_proximity.source missing schema
   views.view.example:display.default.display_options.fields.field_geo_proximity.source_configuration missing schema

Proposed resolution

Declare the three options on the field plugin's schema, matching what the proximity filter's schema already declares for source_configuration. The keys below are the ones the four shipped source plugins store: ManualOriginDefault, ClientLocationOriginFilter, OriginFromProximityFilter and ContextProximityFilter.

views.field.geofield_proximity_field:
  type: views.field.numeric
  label: 'Geofield Proximity Field'
  mapping:
    units:
      type: string
      label: 'Units'
    source:
      type: string
      label: 'Origin source plugin'
    source_configuration:
      type: mapping
      label: 'Origin source configuration'
      mapping:
        origin:
          type: mapping
          mapping:
            lat:
              type: string
            lon:
              type: string
        origin_hidden_flag:
          type: boolean
        origin_summary_flag:
          type: boolean
        source_proximity_filter:
          type: string

The sort's source_configuration declares only source_proximity_filter. It could use the same mapping, since a sort can also take the manual origin. A shared type definition would keep the field, sort and filter from drifting apart again.

Remaining tasks

• Add the schema.
• Add a kernel test that installs a view using the proximity field with strict schema checking on.

User interface changes

None.

API changes

None.

Data model changes

None. Saved views keep the same keys; only their schema is declared.