fix: es6 target

Merge branch 'fix/allow-react-18-and-updates'

fix: export controller

feat(useTreeNodesController): expand multiple items at once

fix(deps): Support React 17

Merge remote-tracking branch 'origin/master'

feat(TreeContainer): support a render function for TreeContainer

fix(staticTreeSource): fix a bug with trail() for nodes without children

Merge pull request #2 from LennardWesterveld/feature/children-not-req…

…uired-for-static-loader

feat(staticTreeSource): allow undefined children in static tree data …

feat(useTreeLoader): allow switching tree source