[data views] Initial creation of abstract data views class (elastic#1…

…61611)

## Summary

Creation of `AbstractDataView` class which provides all functionality
that doesn't expect a full field list upon object creation.

The code remaining in the `DataView` class either loads the field list
or depends upon the loaded field list.

---------

Co-authored-by: Davis McPhee <[email protected]>

src/plugins/data_view_management/public/components/field_editor/field_editor.test.tsx

@@ -119,6 +119,10 @@ describe('FieldEditor', () => {
       fields,
       getFormatterForField: () => ({ params: () => ({}) }),
       getFormatterForFieldNoDefault: () => ({ params: () => ({}) }),
+      upsertScriptedField: () => undefined,
+      setFieldCustomLabel: (name: string, label: string) => {
+        indexPattern.fields.getByName(name)!.customLabel = label;
+      },
     } as unknown as DataView;
   });
 

src/plugins/data_view_management/public/components/field_editor/field_editor.tsx

@@ -822,16 +822,9 @@ export class FieldEditor extends PureComponent<FieldEdiorProps, FieldEditorState
     }
 
     const { redirectAway, indexPatternService } = this.props.services;
-    const fieldExists = !!indexPattern.fields.getByName(field.name);
 
     let oldField: DataViewField['spec'];
-
-    if (fieldExists) {
-      oldField = indexPattern.fields.getByName(field.name)!.spec;
-      indexPattern.fields.update(field);
-    } else {
-      indexPattern.fields.add(field);
-    }
+    indexPattern.upsertScriptedField(field);
 
     if (fieldFormatId) {
       indexPattern.setFieldFormat(field.name, { id: fieldFormatId, params: fieldFormatParams });
@@ -841,7 +834,7 @@ export class FieldEditor extends PureComponent<FieldEdiorProps, FieldEditorState
 
     if (field.customLabel !== customLabel) {
       field.customLabel = customLabel;
-      indexPattern.fields.update(field);
+      indexPattern.setFieldCustomLabel(field.name, customLabel);
     }
 
     return indexPatternService