Add cog setup scripts

This script has the following functionality:
1. Sets up the `out` symlink to point to a default location on disk
2. Copies RBE binaries outside Cog (temporary fix for build stall problem) - b/289391270
3. Exports ANDROID_BUILD_ENVIRONMENT_CONFIG variable to point to googler-cog.json file. This file will be available in aosp-main-with-phones and goog/main and downstream branches.

TESTED=ran the script within and outside the Cog workspace to test it.

Bug: b/295053716
Change-Id: I59cd6d2d5f954be6f7e4ecd7d64de1e63e51b72e

envsetup.sh

@@ -2006,6 +2006,11 @@ function source_vendorsetup() {
             fi
         done
     done
+
+    if [[ "${PWD}" == /google/cog/* ]]; then
+        f="build/make/cogsetup.sh"
+        echo "including $f"; . "$T/$f"
+    fi
 }
 
 function showcommands() {