bug: fix local Authorization header (#284)

* bug: fix local Authorization header

So the problem isn't with Vapid. It's with how we were generating the
other authorization token, specifically differences with how python
and rust were handling things.

Python was converting the hex UAID string into a set of bytes, rust
was converting the 128bit UUID UAID into bytes. Combine that with some
fun regarding the base auth key string, and.. yeah.

I added a test to this to compare the auth key generated by python with
rust, broke the generate and validate functions into the
AuthorizationCheck impl and added a bunch of comments.

Closes #282

.circleci/config.yml

@@ -42,12 +42,16 @@ jobs:
           # ignoring RUSTSEC-2020-0146 => tied to rusoto-core 0.42
           # ignoring RUSTSEC-2021-0003 => blocked tokio update #249
           # ignoring RUSTSEC-2021-0020 => increasing LB security filtering
+          # ignoring RUSTSEC-2021-0078 => blocked on hyper update
+          # ignoring RUSTSEC-2021-0079 => blocked on hyper update
           command: |
             cargo audit \
             --ignore RUSTSEC-2020-0041 \
             --ignore RUSTSEC-2020-0146 \
             --ignore RUSTSEC-2021-0003 \
-            --ignore RUSTSEC-2021-0020
+            --ignore RUSTSEC-2021-0020 \
+            --ignore RUSTSEC-2021-0078 \
+            --ignore RUSTSEC-2021-0079
 
   test:
     docker: