Replace custom socket implementation with SignalR.

Replace MSAL and custom cookie auth with Microsoft.Identity.EntityFramework
Also some UI redesign to accommodate different login experience.

Shogi.UI/Pages/Play/GamePiece.razor.css

@@ -0,0 +1,12 @@
+::deep svg {
+	max-width: 100%;
+	max-height: 100%;
+}
+
+[data-upsidedown] {
+	transform: rotateZ(180deg);
+}
+
+.game-piece {
+	overflow: hidden; /* Because SVGs have weird sizes. */
+}