fix(form-field): ensure that descendants are picked up in Ivy (#17439)
fix(form-field): ensure that descendants are picked up in Ivy (#17439)

Since there's a slight difference in how `ContentChildren` works in Ivy, these changes add the `descendants` flag explicitly to ensure that we pick up all of the relevant elements. Note that we shouldn't need any extra logic, because nesting form fields is invalid.
mmalerba/material2,mmalerba/material2,andrewseguin/material2,crisbeto/material2,crisbeto/material2,josephperrott/material2,josephperrott/material2,andrewseguin/material2,angular/components,andrewseguin/material2,mmalerba/material2,josephperrott/material2,angular/components,josephperrott/material2,mmalerba/material2,Jefiozie/material2,DevVersion/material2,Jefiozie/material2,angular/components,crisbeto/material2,crisbeto/material2,andrewseguin/material2,andrewseguin/material2,Jefiozie/material2,Jefiozie/material2,angular/components,DevVersion/material2,josephperrott/material2,DevVersion/material2,mmalerba/material2,Jefiozie/material2,DevVersion/material2,DevVersion/material2