maint: Add but don't use code-editor.scss which should show line-numbers but is not working yet.

Author: thet

src/code-editor.scss

@@ -0,0 +1,9 @@
+.codejar-linenumbers {
+    font-family: monospace !important;
+    font-size: 1em !important;
+    text-align: left !important;
+    line-height: 1.5 !important;
+    padding: 1em !important;
+    margin: 0.5em 0 !important;
+    overflow: auto !important;
+}