mat-tree should have a filtering feature

#### Feature request, or proposal:
Filtering through tree nodes is a very useful feature, especially to reduce the size of tree and finding out the desired node(s) quickly.

#### What is the expected behavior?
There should be an input box above mat-tree. As you enter the text, it will filter through the tree and renders the tree based on the content in the input box.

#### What is the current behavior?
Filtering feature is not available in mat-tree component.

Comienza revisando el componente mat-tree y su comportamiento público actual para entender cómo se representan y renderizan los nodos del árbol. Define la interacción de filtrado y confirma que introducir texto reduce el árbol mostrado a los nodos coincidentes antes de añadir cobertura para el comportamiento esperado.

Escrito por el modelo de indexación a partir del texto del issue.