[COEPForSharedWorker] Add metrics for COEPForSharedWorker.

COEP is now available on shared workers and we would like
to collect the usage of it via `kCOEPForSharedWorker` in
metrics.

Change-Id: I30716e14ad26261fc2de12137dd4e18977eb0fad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3151259
Reviewed-by: Arthur Sonzogni <[email protected]>
Commit-Queue: Yifan Luo <[email protected]>
Cr-Commit-Position: refs/heads/main@{#923327}
NOKEYCHECK=True
GitOrigin-RevId: d1396702b01e96e5e9bbb493d52b3c7c3cd0916f

blink/public/mojom/web_feature/web_feature.mojom

@@ -3349,6 +3349,9 @@ enum WebFeature {
   kWebShareContainingTitle = 4039,
   kWebShareContainingText = 4040,
   kWebShareContainingUrl = 4041,
+  kCoepNoneSharedWorker = 4042,
+  kCoepRequireCorpSharedWorker = 4043,
+  kCoepCredentiallessSharedWorker = 4044,
 
   // Add new features immediately above this line. Don't change assigned
   // numbers of any item, and don't reuse removed slots.