LP1822414 Ang date select readOnly & fixes

LP1822414 Ang date select readOnly & fixes

Adds an @Input() readOnly field to eg-date-select.  When set, the date
value will be displayed as plain text - no widget.

Teach the eg-fm-editor to pass the readOnly flag to the eg-date-select.

Includes sandbox example.

Fixes a display issue where the date select calendar button was bigger
than the paired input group adding text input, because the material
icon was too big.

2019-07-31 rebasing note: the style added in the original patch was
moved to data-select.component.css.

Signed-off-by: Bill Erickson <berickxx@gmail.com>
Signed-off-by: Jane Sandberg <sandbej@linnbenton.edu>
Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>