Add removedValues into onChange clear action meta

The similar actions `remove-value` and `pop-value` have `removedValue`
in their `onChange` meta arguments.

It would be reasonable to pass the whole `this.state.selectValue` as
`removedValues` assuming that all selected values are removed upon `clear`.

This will help some client code to add additional logic in `onChange`
handlers like filtering of fixed values to preseve after `clear` without
referring to `options` array.

.changeset/pink-cats-mate.md

@@ -0,0 +1,5 @@
+---
+"react-select": patch
+---
+
+Add `removedValues` that points to the current selection into a meta of onChange callback when clearing value.

packages/react-select/src/Select.js

@@ -872,7 +872,11 @@ export default class Select extends Component<Props, State> {
     this.focusInput();
   };
   clearValue = () => {
-    this.onChange(this.props.isMulti ? [] : null, { action: 'clear' });
+    const { selectValue } = this.state;
+    this.onChange(this.props.isMulti ? [] : null, {
+      action: 'clear',
+      removedValues: selectValue,
+    });
   };
   popValue = () => {
     const { isMulti } = this.props;

packages/react-select/src/__tests__/Select.test.js

@@ -1661,6 +1661,7 @@ test('should call onChange with `null` on hitting backspace when backspaceRemove
   expect(onChangeSpy).toHaveBeenCalledWith(null, {
     action: 'clear',
     name: 'test-input-name',
+    removedValues: [],
   });
 });
 
@@ -2308,6 +2309,7 @@ test('clear select by clicking on clear button > should not call onMenuOpen', ()
   expect(onChangeSpy).toBeCalledWith([], {
     action: 'clear',
     name: BASIC_PROPS.name,
+    removedValues: [{ label: '0', value: 'zero' }],
   });
 });
 
@@ -2631,6 +2633,7 @@ test('to clear value when hitting escape if escapeClearsValue and isClearable ar
   expect(onInputChangeSpy).toHaveBeenCalledWith(null, {
     action: 'clear',
     name: BASIC_PROPS.name,
+    removedValues: [{ label: '0', value: 'zero' }],
   });
 });