Web IDE: Add solarized light theme

Add solarized light syntax highlighting theme for Web IDE

app/assets/javascripts/ide/lib/themes/index.js

 import white from './white';
 import dark from './dark';
 import monokai from './monokai';
+import solarizedLight from './solarized_light';
 import solarizedDark from './solarized_dark';
 
 export const themes = [
@@ -12,6 +13,10 @@ export const themes = [
     name: 'dark',
     data: dark,
   },
+  {
+    name: 'solarized-light',
+    data: solarizedLight,
+  },
   {
     name: 'solarized-dark',
     data: solarizedDark,

changelogs/unreleased/201930-webide-solarized.yml

+---
+title: Solarized light syntax highlighting theme for the Web IDE
+merge_request: 30989
+author:
+type: added