[TreeView] New instance and publicAPI method: getItem

[flaviendelangle]

Closes #10957

Not sure why but I can't use the PR package on Codesandbox 🤔
Here is a basic usage of the method if you want to test it:

import * as React from 'react';
import Box from '@mui/material/Box';
import Stack from "@mui/material/Stack";
import Typography from "@mui/material/Typography";
import { TreeViewBaseItem } from '@mui/x-tree-view/models';
import { RichTreeView } from '@mui/x-tree-view/RichTreeView';
import {useTreeViewApiRef} from "@mui/x-tree-view";


const MUI_X_PRODUCTS: TreeViewBaseItem[] = [
    {
        id: 'grid',
        label: 'Data Grid',
        children: [
            { id: 'grid-community', label: '@mui/x-data-grid' },
            { id: 'grid-pro', label: '@mui/x-data-grid-pro' },
            { id: 'grid-premium', label: '@mui/x-data-grid-premium' },
        ],
    },
    {
        id: 'pickers',
        label: 'Date and Time Pickers',
        children: [
            { id: 'pickers-community', label: '@mui/x-date-pickers', },
            { id: 'pickers-pro', label: '@mui/x-date-pickers-pro' },
        ],
    },
];

export default function BasicRichTreeView() {
    const [lastExpandedItem, setLastExpandedItem] = React.useState<string | null>(null)
    const apiRef = useTreeViewApiRef()

    const handleNodeExpansionToggle = React.useCallback((    event: React.SyntheticEvent,
                                                             nodeId: string,
                                                             isExpanded: boolean,) => {
        if (isExpanded) {
            const item = apiRef.current!.getItem(nodeId);
            setLastExpandedItem(item.label)
        }
    }, [apiRef])

    return (
        <Stack spacing={2}>
            <Typography>{lastExpandedItem == null ? 'No item expanded recently' : `Last expanded item: ${lastExpandedItem}`}</Typography>
            <Box sx={{ height: 220, flexGrow: 1, maxWidth: 400 }}>
                <RichTreeView items={MUI_X_PRODUCTS} apiRef={apiRef} onNodeExpansionToggle={handleNodeExpansionToggle} />
            </Box>
        </Stack>
    );
}

[flaviendelangle]

I scoped the node state because having 3 elements at the root was starting to be messy

[mui-bot]

Deploy preview: https://deploy-preview-12251--material-ui-x.netlify.app/

Generated by 🚫 dangerJS against ec368ce

[flaviendelangle]

The typing was weird, it was only taking a single plugin
Now by default the type is the one of the default plugins (which are used by both the rich and the simple tree view)
but you can pass a generic to support more plugins (not useful for now, will become useful with RichTreeView-only plugins if they end up having public methods)

[flaviendelangle]

This ensure the public API is always a subset of the private one

[noraleonte]

LGTM 🎉 Thanks for doing this 💯