Add option to render main view as modal

packages/rocketchat-theme/assets/stylesheets/base.less

@@ -1726,6 +1726,10 @@ a.github-fork {
 			.transform(translateX(0));
 		}
 	}
+	&.main-modal {
+		left: 0px;
+		margin-right: 0px;
+	}
 	.container-fluid {
 		padding-top: 0;
 	}

packages/rocketchat-ui-master/master/main.html

@@ -56,13 +56,17 @@
 					<div class="connection-status">
 						{{> status}}
 					</div>
-					<div class="flex-tab-bar" role="toolbar">
-						{{> flexTabBar}}
-					</div>
-					<div class="main-content {{flexOpened}} {{flexOpenedRTC1}} {{flexOpenedRTC2}}">
+					{{#unless modal}}
+						<div class="flex-tab-bar" role="toolbar">
+							{{> flexTabBar}}
+						</div>
+					{{/unless}}
+					<div class="main-content {{flexOpened}} {{flexOpenedRTC1}} {{flexOpenedRTC2}} {{#if modal}}main-modal{{/if}}">
 						{{> Template.dynamic template=center}}
 					</div>
-					{{> sideNav }}
+					{{#unless modal}}
+						{{> sideNav }}
+					{{/unless}}
 				</div>
 				{{> audioNotification }}
 			{{/unless}}