[INTERNAL] `<ListItemBase />` component should be the base of any List Item component that the
Momentum Library requires (i.e. SpaceListItem, SearchResultListItem etc.). This component acts like
a skeleton that helps you develop more complex ListItems. Below are a few examples on how to use it
and what you can achieve.

## Structure

The structure of the component is as follows:

```
+---------------+----------------+-------------+
| Start Section | Middle Section | End Section |
+---------------+----------------+-------------+

or

+---------------+----------------+-------------+
|                  Fill Section                |
+---------------+----------------+-------------+
```

The 4 sections can be mixed together as needed. We provide a `<ListItemBaseSection />` component
that will handle spacing and padding accordingly.

## Simple example

```js
<ListItemBase>
  <ListItemBaseSection position="start">
    <Avatar title="Webex User" />
  </ListItemBaseSection>
  <ListItemBaseSection position="fill">Webex User</ListItemBaseSection>
</ListItemBase>
```

## Complex example

```js
<ListItemBase size={50} shape="isPilled">
  <ListItemBaseSection position="start">
    <Avatar title="John Adams" size={32} presence={PresenceType.Active} />
  </ListItemBaseSection>
  <ListItemBaseSection position="fill">Text goes here</ListItemBaseSection>
  <ListItemBaseSection position="end">
    <Icon name="placeholder" scale={16} />
  </ListItemBaseSection>
</ListItemBase>
```