[test/wild] Summarize failures at the top level, in text and HTML.

The text can be used as a starting point for --not-shell and --not-osh.

- Write version text, like test/spec.sh does.
  - Extracted a function into test/common.sh and added an include guard.
- Add flags, as well as explicit input and output directories

test/common.sh

@@ -1,7 +1,12 @@
 #!/bin/bash
 #
 # Usage:
-#   ./common.sh <function name>
+#   source test/common.sh
+
+# Include guard.
+test -n "${__TEST_COMMON_SH:-}" && return
+readonly __TEST_COMMON_SH=1
+
 
 # TODO: Remove/rename this.  The release process might use the release binary
 # instead of this dev binary.  test/spec.sh already has its own scheme.
@@ -91,6 +96,20 @@ run-other-suite-for-release() {
   fi
 }
 
+date-and-git-info() {
+  date
+  echo
+
+  if test -d .git; then
+    local branch=$(git rev-parse --abbrev-ref HEAD)
+    local hash=$(git rev-parse $branch)
+    echo "oil repo: $hash on branch $branch"
+  else
+    echo "(not running from git repository)"
+  fi
+  echo
+}
+
 if test "$(basename $0)" = 'common.sh'; then
   "$@"
 fi