✨ (bootsier): Añade AdminLTE 4 y Bootstrap Icons

Integra AdminLTE 4.0.0 (SCSS y JS), Bootstrap Icons 1.13.1 y las fuentes
Source Sans 3 VF; reorganiza los SCSS del tema con la nueva estructura
de *pagetop-build*.

extensions/pagetop-bootsier/assets/bootstrap-5.3.8/scss/tests/sass-true/runner.js

@@ -0,0 +1,17 @@
+'use strict'
+
+const fs = require('node:fs')
+const path = require('node:path')
+const { runSass } = require('sass-true')
+
+module.exports = (filename, { describe, it }) => {
+  const data = fs.readFileSync(filename, 'utf8')
+  const TRUE_SETUP = '$true-terminal-output: false; @import "true";'
+  const sassString = TRUE_SETUP + data
+
+  runSass(
+    { describe, it, sourceType: 'string' },
+    sassString,
+    { loadPaths: [path.dirname(filename)] }
+  )
+}