refactor(input): mirror placeholder in data attribute (#19831)
refactor(input): mirror placeholder in data attribute (#19831)

This is a prerequisite to make landing #10466 easier in g3. Mirrors the native placeholder value in a data attribute so that we can read it even when it has been removed.
andrewseguin/material2,DevVersion/material2,josephperrott/material2,josephperrott/material2,angular/components,josephperrott/material2,DevVersion/material2,andrewseguin/material2,DevVersion/material2,crisbeto/material2,mmalerba/material2,Jefiozie/material2,Jefiozie/material2,Jefiozie/material2,crisbeto/material2,crisbeto/material2,josephperrott/material2,angular/components,Jefiozie/material2,DevVersion/material2,angular/components,crisbeto/material2,josephperrott/material2,mmalerba/material2,andrewseguin/material2,mmalerba/material2,angular/components,mmalerba/material2,Jefiozie/material2,andrewseguin/material2,andrewseguin/material2,mmalerba/material2,DevVersion/material2