Chore: Emit theme token usage metrics (#72500)

* create rule to find instances of theme variables

* emit theme token usage metrics

* move awking into script

* make sure theme usage is covering ts and tsx files, remove commented lines

packages/grafana-eslint-rules/index.cjs

@@ -1,7 +1,9 @@
 const noAriaLabelSelectors = require('./rules/no-aria-label-e2e-selectors.cjs');
+const themeTokenUsage = require('./rules/theme-token-usage.cjs');
 
 module.exports = {
   rules: {
     'no-aria-label-selectors': noAriaLabelSelectors,
+    'theme-token-usage': themeTokenUsage,
   },
 };