also escape back-ticks and backslashes in text nodes in SSR code (#616)

src/generators/server-side-rendering/visitors/Text.ts

@@ -3,5 +3,5 @@ import Block from '../Block';
 import { Node } from '../../../interfaces';
 
 export default function visitText ( generator: SsrGenerator, block: Block, node: Node ) {
-	generator.append( node.data.replace( /\${/g, '\\${' ) );
+	generator.append( node.data.replace( /(\${|`|\\)/g, '\\$1' ) );
 }

test/runtime/samples/escape-template-literals/_config.js

@@ -0,0 +1,3 @@
+export default {
+	html: '<code>`${foo}\\n`</code>'
+};

test/runtime/samples/escape-template-literals/main.html

@@ -0,0 +1 @@
+<code>`${foo}\n`</code>