chore: added type information to core/field_dropdown.ts (#6550)

* chore: added generator type to `core/field_dropdown.ts` and updated affected files

* chore: added type to ARROW_CHAR in `core/field_dropdown.ts`

* chore: cleaned up misc 'AnyDuringMigration' cases and related comments

* fix: misc adjustments from PR feedback

* Fix: simplified `getOptions`

* fix: removed outdated arrow and cleaned up formatting

* fix: cleanup format after rebase

core/blockly.ts

@@ -57,7 +57,7 @@ import {Field} from './field.js';
 import {FieldAngle} from './field_angle.js';
 import {FieldCheckbox} from './field_checkbox.js';
 import {FieldColour} from './field_colour.js';
-import {FieldDropdown} from './field_dropdown.js';
+import {FieldDropdown, MenuGenerator, MenuGeneratorFunction, MenuOption} from './field_dropdown.js';
 import {FieldImage} from './field_image.js';
 import {FieldLabel} from './field_label.js';
 import {FieldLabelSerializable} from './field_label_serializable.js';
@@ -651,7 +651,7 @@ export {Field};
 export {FieldAngle};
 export {FieldCheckbox};
 export {FieldColour};
-export {FieldDropdown};
+export {FieldDropdown, MenuGenerator, MenuGeneratorFunction, MenuOption};
 export {FieldImage};
 export {FieldLabel};
 export {FieldLabelSerializable};