Demos: Remove deprecated button APIs

Remove usage of deprecated button options:
* `icons`: https://jqueryui.com/upgrade-guide/1.12/#deprecated-icons-options-in-favor-of-icon-and-iconposition
* `text`: https://jqueryui.com/upgrade-guide/1.12/#deprecated-text-option-in-favor-of-showlabel

Fixes gh-2295

Author: mgol

demos/autocomplete/combobox.html

@@ -78,10 +78,8 @@
 					.tooltip()
 					.appendTo( this.wrapper )
 					.button({
-						icons: {
-							primary: "ui-icon-triangle-1-s"
-						},
-						text: false
+						icon: "ui-icon-triangle-1-s",
+						showLabel: false
 					})
 					.removeClass( "ui-corner-all" )
 					.addClass( "custom-combobox-toggle ui-corner-right" )

demos/tooltip/video-player.html

@@ -63,10 +63,8 @@
 
 		$( "button" ).each(function() {
 			var button = $( this ).button({
-				icons: {
-					primary: $( this ).data( "icon" )
-				},
-				text: !!$( this ).attr( "title" )
+				icon: $( this ).data( "icon" ),
+				showLabel: !!$( this ).attr( "title" )
 			});
 			button.not( ".menu" ).on( "click", function() {
 				notify( button );

tests/visual/tooltip/tooltip.html

@@ -72,15 +72,11 @@
 
 		$( "#button1" ).button();
 		$( "#button2" ).button({
-			icons: {
-				primary: "ui-icon-wrench"
-			}
+			icon: "ui-icon-wrench"
 		});
 		$( "#button3, #button4" ).button({
-			icons: {
-				primary: "ui-icon-wrench"
-			},
-			text: false
+			icon: "ui-icon-wrench",
+			showLabel: false
 		});
 		$( "#buttons" ).tooltip({
 			position: {