feat: Add support for dark mode node icons and colors (#9412)

Co-authored-by: Giulio Andreini <g.andreini@gmail.com>

packages/nodes-base/nodes/Markdown/markdown.svg

@@ -1 +1,3 @@
-<svg xmlns="http://www.w3.org/2000/svg" width="256" height="158" preserveAspectRatio="xMidYMid"><path d="M238.371 157.892H18.395C8.431 157.892 0 149.462 0 139.497V18.395C0 8.431 8.431 0 18.395 0h219.21C247.569 0 256 8.431 256 18.395v121.102c0 9.964-7.665 18.395-17.629 18.395M18.395 12.263c-3.066 0-6.132 3.066-6.132 6.132v121.102c0 3.832 3.066 6.132 6.132 6.132h219.21c3.832 0 6.132-3.066 6.132-6.132V18.395c0-3.832-3.066-6.132-6.132-6.132zM36.79 121.102V36.79h24.527l24.527 30.66 24.527-30.66h24.527v84.312h-24.527V72.814l-24.527 30.66-24.527-30.66v48.288zm154.06 0-36.79-40.623h24.527V36.79h24.527v42.923h24.527z"/></svg>
+<svg width="40" height="40" viewBox="0 0 40 40" fill="none" xmlns="http://www.w3.org/2000/svg">
+<path d="M37.1164 32.6187H2.88357C2.5049 32.6187 2.12993 32.5441 1.78008 32.3992C1.43023 32.2543 1.11234 32.0419 0.844579 31.7741C0.576815 31.5064 0.364412 31.1885 0.219499 30.8386C0.0745858 30.4888 0 30.1138 0 29.7351V10.8836C0 10.1188 0.303804 9.38535 0.844579 8.84458C1.38535 8.3038 2.1188 8 2.88357 8H37.1164C37.4951 8 37.8701 8.07459 38.2199 8.2195C38.5698 8.36441 38.8877 8.57681 39.1554 8.84458C39.4232 9.11234 39.6356 9.43023 39.7805 9.78008C39.9254 10.1299 40 10.5049 40 10.8836V29.7318C40.0002 30.1106 39.9258 30.4858 39.781 30.8358C39.6362 31.1859 39.4238 31.5039 39.156 31.7719C38.8882 32.0398 38.5703 32.2524 38.2203 32.3974C37.8703 32.5424 37.4952 32.6187 37.1164 32.6187ZM9.61413 26.8482V19.3476L13.4611 24.1563L17.3064 19.3476V26.8482H21.1534V13.7721H17.3064L13.4611 18.5809L9.61413 13.7721H5.76715V26.8516L9.61413 26.8482ZM35.3863 20.3094H31.5393V13.7705H27.694V20.3094H23.847L29.6158 27.0416L35.3863 20.3094Z" fill="#383839"/>
+</svg>