Use embedded SVG instead of fonts for icons

The [downsides of icon fonts] are well-documented, and also, why ship all of
the icons when it only uses 14?

[downsides of icon fonts]: https://speakerdeck.com/ninjanails/death-to-icon-fonts

Cargo.lock

@@ -622,6 +622,12 @@ version = "1.0.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
 
+[[package]]
+name = "font-awesome-as-a-crate"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "932dcfbd51320af5f27f1ba02d2e567dec332cac7d2c221ba45d8e767264c4dc"
+
 [[package]]
 name = "form_urlencoded"
 version = "1.2.1"
@@ -1352,6 +1358,7 @@ dependencies = [
  "ammonia",
  "anyhow",
  "elasticlunr-rs",
+ "font-awesome-as-a-crate",
  "handlebars",
  "hex",
  "log",