Center align block katex equations

Author: mjbvz

src/vs/workbench/contrib/chat/browser/chatContentParts/media/chatMarkdownPart.css

@@ -16,6 +16,7 @@
 	}
 
 	.katex-display .katex {
+		margin: auto;
 		width: fit-content;
 		overflow: hidden;
 	}