feat(material/chips): update chip-list describedby to match input

[RobertAKARobin]

Updates MatChipList to be consistent with MatInput, and fixes ExpressionChangedAfterItHasBeenCheckedError that occurs when chip-lists are content-projected into a mat-form-field, e.g.

<mat-form-field>
    <ng-content select="mat-chip-list"></ng-content>
    <mat-hint>foo</mat-hint>
</mat-form-field>

My use-case was creating a wrapper around mat-form-field to house various Mat-* formcontrol types.

MatSelect could use the same update.

[devversion]

LGTM. Thank you!

Really another feature as part of this PR is that users are now able to add additional
accessibility descriptions (through aria-describedby) on the select, without it being accidentally overidden.

cc. @crisbeto for an additional review.

[crisbeto]

LGTM

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