infra: Add links to the 3 main branch consoles to Milo's console header.

Adds links to trunk, beta, & stable consoles to the header. That should
make all 3 discoverable from most every console.

Bug: None
Change-Id: I269c07ba93f7599b5c9eab588dc1a698cfb9a9f4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2050867Reviewed-by: Garrett Beaty <gbeaty@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#740378}

infra/config/consoles/chromium-header.textpb

@@ -161,6 +161,24 @@ links {
     alt: "ChromiumOS console"
   }
 }
+links {
+  name: "Branch Consoles"
+  links {
+    text: "beta"
+    url: "/p/chromium/g/main-beta/console"
+    alt: "Beta branch console"
+  }
+  links {
+    text: "stable"
+    url: "/p/chromium/g/main-stable/console"
+    alt: "Stable branch console"
+  }
+  links {
+    text: "trunk"
+    url: "/p/chromium/g/main/console"
+    alt: "Trunk (ToT) console"
+  }
+}
 links {
   name: "Tryservers"
   links {