tools: Replace copy-pasta scripts

There were a bunch of helper scripts to build a go tool and run it.
Replace these with a single 'run' command that takes the tool name and arguments.

Helps reduce maintainance, file spew.

Also add the 'tools/bin' directory to .gitignore. These are the cached tool binaries.

Bug: dawn:1339
Change-Id: I012c966736b4d93949f6142c342cdcfefa9f0083
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/86063
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>

tools/run

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+# Copyright 2022 The Tint Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -e # Fail on any error.
+
+SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd )"
+TOOL="$1"
+BINARY="${SCRIPT_DIR}/bin/${TOOL}"
+
+if [ ! -x "$(which go)" ] ; then
+  echo "error: go needs to be on \$PATH to use $0"
+  exit 1
+fi
+
+function list_tools() {
+  echo "Available tools:"
+  ls "${SCRIPT_DIR}/src/cmd"
+}
+
+function show_usage() {
+  echo "run <tool> <args>"
+  echo
+  echo "builds and runs the go tool in <dawn>/tools/src/cmd"
+  echo
+  list_tools
+  exit 1
+}
+
+if [ -z "${TOOL}" ]; then
+  show_usage
+fi
+
+if [ ! -d "${SCRIPT_DIR}/src/cmd/${TOOL}" ]; then
+  show_usage
+fi
+
+# Rebuild the binary.
+# Note, go caches build artifacts, so this is quick for repeat calls
+pushd "${SCRIPT_DIR}/src" > /dev/null
+    go build -o "${BINARY}" "./cmd/${TOOL}"
+popd > /dev/null
+
+"${BINARY}" "${@:2}"