Light mode: more fixes & cleanup:

- Remove lots more unused files
- Make light mode toggles for Exchange and Wallet images
- Change layout for exchanges and wallets to work better at some screen
  widths (between mobile and full 1080p)
- Fix light mode styles for some dev tools, carbon calculator, Edit
  button, footer, etc.

template/page-xrpl-overview.html.jinja

@@ -59,7 +59,7 @@
         <p class="mb-0">{% trans %}Anyone can operate a validator; currently, over 150 <a href="https://livenet.xrpl.org/network/validators" target="_blank">validators</a> are active on the ledger, operated by universities, exchanges, businesses, and individuals. Additionally, the consensus protocol ensures the blockchain becomes more decentralized over time as the validator pool grows.{% endtrans %}</p>
       </div>
       <div class="col-new mb-16-sm">
-        <img class="mw-100" src="./img/graphics/validator.svg">
+        <img class="mw-100" id="validator-graphic" alt="(Graphic: Validators in Consensus)">
       </div>
     </div>
   </section>