chore(assets): remove dead icon assets and consolidate icons/

Delete zero-referenced leftovers (31 img SVGs, duplicate top-level
vip badges, favicon/icon/person_background pngs, assets/fonts/,
tmp-debug/, gutenberg-extend.js and the FA eot/ttf/svg font formats)
and give icon-purpose SVGs one home in assets/icons/ (upload-add,
default favicon/logo, playing, user-certification) with every reference
updated. Icon SVG files were audited by name across PHP/CSS/JS before
deletion.

assets/icons/upload-add.svg

@@ -0,0 +1,3 @@
+<svg viewBox="-3600 -3600 8200 8200" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" style="background: rgba(160,160,160,.05);">
+    <path fill="#757575" d="M530.517333 8.618667c19.2 0 34.645333 15.530667 34.645334 34.645333v415.573333h415.573333a34.645333 34.645333 0 1 1 0 69.205334h-415.573333v415.573333a34.645333 34.645333 0 1 1-69.205334 0v-415.573333H80.298667a34.645333 34.645333 0 0 1 0-69.205334h415.573333V43.178667c0-19.114667 15.445333-34.645333 34.56-34.645334z" opacity=".2" />
+</svg>