[UA-CH] Rename Accept-CH tokens

Bring tokens inline with Section 3.1 of the Client Hints spec, which
recommends tokens be the same as the header name they're associated
with.

Also fixing the *copious* tests associated with this change...

Intent to Remove: https://groups.google.com/u/1/a/chromium.org/g/blink-dev/c/t-S9nnos9qU

Bug: 1153688
Change-Id: I2bfe038abe887713d56ef835e8f9d61246001040
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2595089
Reviewed-by: Maksim Orlovich <morlovich@chromium.org>
Reviewed-by: Yoav Weiss <yoavweiss@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Aaron Tagliaboschi <aarontag@chromium.org>
Cr-Commit-Position: refs/heads/master@{#846075}

client-hints/accept-ch-cache-revalidation.https.html.headers

@@ -1 +1 @@
-Accept-CH: dpr,device-memory,viewport-width,rtt,downlink,ect,lang,ua,ua-arch,ua-platform,ua-platform-version,ua-model
+Accept-CH: dpr,device-memory,viewport-width,rtt,downlink,ect,lang,sec-ch-ua,sec-ch-ua-arch,sec-ch-ua-platform,sec-ch-ua-platform-version,sec-ch-ua-model

client-hints/sec-ch-quotes.https.html.headers

@@ -1 +1 @@
-Accept-CH: ua,ua-arch,ua-platform,ua-platform-version,ua-model
+Accept-CH: sec-ch-ua,sec-ch-ua-arch,sec-ch-ua-platform,sec-ch-ua-platform-version,sec-ch-ua-model