Make it more obvious that the add reaction button is not an emoji

fixes #1301

resources/icons/ui/smile-add.svg

@@ -0,0 +1 @@
+<svg width="24" height="24" fill="none" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><path d="M17.5 12a5.5 5.5 0 1 1 0 11 5.5 5.5 0 0 1 0-11ZM12 2c5.524 0 10.002 4.478 10.002 10.002 0 .263-.01.524-.03.782a6.507 6.507 0 0 0-1.475-1.052 8.501 8.501 0 1 0-8.765 8.767 6.5 6.5 0 0 0 1.05 1.474c-.257.02-.518.03-.782.03-5.524 0-10.002-4.478-10.002-10.001C1.998 6.477 6.476 1.999 12 1.999Zm5.5 12-.09.008a.5.5 0 0 0-.402.402L17 14.5V17L14.498 17l-.09.008a.5.5 0 0 0-.402.402l-.008.09.008.09a.5.5 0 0 0 .402.402l.09.008H17v2.503l.008.09a.5.5 0 0 0 .402.402l.09.008.09-.008a.5.5 0 0 0 .402-.402l.008-.09V18l2.504.001.09-.008a.5.5 0 0 0 .402-.402l.008-.09-.008-.09a.5.5 0 0 0-.402-.402l-.09-.008H18v-2.5l-.008-.09a.5.5 0 0 0-.402-.403L17.5 14Zm-9.038.785a4.494 4.494 0 0 0 2.63 1.626 6.449 6.449 0 0 0-.079 1.51 5.983 5.983 0 0 1-3.73-2.208.75.75 0 0 1 1.179-.928ZM9 8.75a1.25 1.25 0 1 1 0 2.499A1.25 1.25 0 0 1 9 8.75Zm6 0a1.25 1.25 0 1 1 0 2.499 1.25 1.25 0 0 1 0-2.499Z" fill="#212121"/></svg>

resources/qml/MessageView.qml

@@ -138,7 +138,7 @@ Item {
                     visible: room ? room.permissions.canSend(MtxEvent.Reaction) : false
                     width: 16
                     hoverEnabled: true
-                    image: ":/icons/icons/ui/smile.svg"
+                    image: ":/icons/icons/ui/smile-add.svg"
                     ToolTip.visible: hovered
                     ToolTip.delay: Nheko.tooltipDelay
                     ToolTip.text: qsTr("React")

resources/res.qrc

@@ -47,6 +47,7 @@
         <file>icons/ui/send.svg</file>
         <file>icons/ui/settings.svg</file>
         <file>icons/ui/smile.svg</file>
+        <file>icons/ui/smile-add.svg</file>
         <file>icons/ui/speech-bubbles.svg</file>
         <file>icons/ui/star.svg</file>
         <file>icons/ui/sticky-note-solid.svg</file>