make kube::util::find-binary not dependent on bazel-out/ structure

Implement an aspect that outputs go_build_mode metadata for go binaries,
and use that during binary selection.

hack/lib/util.sh

@@ -207,19 +207,16 @@ kube::util::find-binary-for-platform() {
       "${KUBE_ROOT}/_output/dockerized/go/bin/${lookfor}"
     );
   fi
-  # Also search for binary in bazel build tree.
-  # The bazel go rules place some binaries in subtrees like
-  # "bazel-bin/source/path/linux_amd64_pure_stripped/binaryname", so make sure
-  # the platform name is matched in the path.
-  while IFS=$'\n' read -r location; do
-    locations+=("$location");
-  done < <(find "${KUBE_ROOT}/bazel-bin/" -type f -executable \
-    \( -path "*/${platform/\//_}*/${lookfor}" -o -path "*/${lookfor}" \) 2>/dev/null || true)
-  # search for executables for non-GNU versions of find (eg. BSD)
-  while IFS=$'\n' read -r location; do
-    locations+=("$location");
-  done < <(find "${KUBE_ROOT}/bazel-bin/" -type f -perm -111 \
-    \( -path "*/${platform/\//_}*/${lookfor}" -o -path "*/${lookfor}" \) 2>/dev/null || true)
+
+  # Also search for binary in bazel build tree if bazel-out/ exists.
+  if [[ -d "${KUBE_ROOT}/bazel-out" ]]; then
+    while IFS=$'\n' read -r bin_build_mode; do
+      if grep -q "${platform}" "${bin_build_mode}"; then
+        # drop the extension to get the real binary path.
+        locations+=("${bin_build_mode%.*}")
+      fi
+    done < <(find "${KUBE_ROOT}/bazel-out/" -name "${lookfor}.go_build_mode")
+  fi
 
   # List most recently-updated location.
   local -r bin=$( (ls -t "${locations[@]}" 2>/dev/null || true) | head -1 )