✨(react) add multi select

Adding this new variant makes necessary to reorganize the files to keep
a clear separations of concerns. As of now Select/index.tsx is just an
entrypoint to render either the mono or multi variant of the select.

packages/react/src/components/Forms/Select/multi.mdx

@@ -0,0 +1,112 @@
+import { Canvas, Meta, Story, Source, ArgTypes } from '@storybook/blocks';
+import { Select } from "./index";
+import * as Stories from './multi.stories';
+
+<Meta of={Stories} name="Docs"/>
+
+# Multi-Select
+
+Cunningham provides a versatile Multi-Select component that you can use in your forms. This component follows the [ARIA design pattern](https://www.w3.org/WAI/ARIA/apg/patterns/combobox/examples/combobox-autocomplete-list/)
+using [Downshift](https://www.downshift-js.com/), so that mean there is no `select` wrapped inside it.
+
+The Multi-Select leverages the regular [Select](?path=/docs/components-forms-select-mono--docs) component, you just have to add the `multi` props.
+
+<Canvas>
+  <Story id="components-forms-select-multi--full-width"/>
+</Canvas>
+
+## Options
+
+The `options` props works the same as the `options` props in the [Select](?path=/docs/components-forms-select-mono--docs#options) component.
+
+## Searchable
+
+You can enable the text live filtering simply by using the `searchable` props.
+
+<Canvas sourceState="shown">
+  <Story id="components-forms-select-multi--searchable-uncontrolled"/>
+</Canvas>
+
+## States
+
+You can use the following props to change the state of the Multi-Select component by using the `state` props.
+
+<Canvas sourceState="shown">
+  <Story id="components-forms-select-multi--success"/>
+</Canvas>
+
+<Canvas sourceState="shown">
+  <Story id="components-forms-select-multi--error"/>
+</Canvas>
+
+## Disabled
+
+As a regular select, you can disable it by using the `disabled` props. In this mode the user can't select nor unselect existing options.
+
+<Canvas sourceState="shown">
+  <Story id="components-forms-select-multi--disabled"/>
+</Canvas>
+
+## Texts
+
+As the component uses [Field](?path=/docs/components-forms-field--docs), you can use the `text` props to provide a description of the checkbox.
+
+<Canvas sourceState="shown">
+  <Story id="components-forms-select-multi--with-text"/>
+</Canvas>
+
+## Width
+
+By default, the Multi-Select has a default width, like all inputs. But you can force it to take the full width of its container by using the `fullWidth` props.
+
+<Canvas sourceState="shown">
+  <Story id="components-forms-select-multi--full-width"/>
+</Canvas>
+
+## Clearable
+
+By default, the Multi-Select is clearable ( the cross icon on the right is shown ). You can disable it by using the `clearable` props.
+
+<Canvas sourceState="shown">
+  <Story id="components-forms-select-multi--not-clearable"/>
+</Canvas>
+
+## Disabled options
+
+You can disable some options by using the `disabled` props on the `Option` object.
+
+<Canvas sourceState="shown">
+  <Story id="components-forms-select-multi--disabled-options"/>
+</Canvas>
+
+## Hide label
+
+For some reasons you might want to hide the label of the Multi-Select. You can do that by using the `hideLabel` props.
+
+> It is important for accessibility to always have a label for your inputs. Keep in mind that setting `hideLabel` to `true`, will only hide the label visually, but it will still be available for screen readers in the DOM.
+
+<Canvas sourceState="shown">
+  <Story id="components-forms-select-multi--hidden-label"/>
+</Canvas>
+
+## Controlled / Non Controlled
+
+Like a native select, you can use the Select component in a controlled or non controlled way. You can see the example below
+using the component in a controlled way.
+
+<Canvas sourceState="shown">
+  <Story id="components-forms-select-multi--controlled"/>
+</Canvas>
+
+## Props
+
+They are the same as the [Select](?path=/docs/components-forms-select-mono--docs#props) component.
+
+## Design tokens
+
+They are the same as the [Select](?path=/docs/components-forms-select-mono--docs#design-tokens) component plus the following:
+
+| Token        	| Description                 	|
+|---------------	|-----------------------------	|
+| multi-pill-background-color	| Background color of the pills of the multi select    	|
+| multi-pill-border-radius	| Border radius of the pills of the multi select    	|