feat(main): Add base theme: This is the falcon theme out of the box.

This is falcon v3.1.2

_dev/webpack/webpack.common.js

@@ -0,0 +1,22 @@
+const { extractScss, extractJs, extractImages, extractFonts, externals, extractVendorsChunks, preloadFonts, resolve } = require('./webpack.parts');
+const { merge } = require("webpack-merge");
+
+exports.commonConfig = ({ mode, port, publicPath, siteURL, getOutput, getEntry, entriesArray, stats, devServer }) => (
+  merge(
+    {
+      mode,
+      entry: getEntry(entriesArray),
+      output: getOutput({ mode, publicPath, siteURL, port, devServer }),
+      target: 'web',
+    },
+    preloadFonts(),
+    externals(),
+    extractScss({ mode }),
+    extractJs(),
+    extractImages({ publicPath }),
+    extractFonts({ publicPath }),
+    extractVendorsChunks(),
+    resolve(),
+    (stats ? { stats } : {})
+  )
+);