feat(icons): Add motorbike icon (#3371)

* Add `motorbike` and `dirtbike` icons

* Renamed `dirtbike` to `dirt-bike`

* Deleted `dirt-bike` in order to move it to a separate PR

* Update motorbike.svg

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Co-authored-by: Eric Fennis <eric.fennis@gmail.com>

Author: 2 people

icons/motorbike.json

@@ -0,0 +1,22 @@
+{
+  "$schema": "../icon.schema.json",
+  "contributors": [
+    "jamiemlaw"
+  ],
+  "tags": [
+    "moto",
+    "motorcycle",
+    "transport",
+    "vehicle",
+    "drive",
+    "ride",
+    "trip",
+    "race",
+    "racing",
+    "journey",
+    "delivery"
+  ],
+  "categories": [
+    "transportation"
+  ]
+}