Fix for Boolean types (#5379) (#5466)

The packing/unpacking steps for Boolean values was failing because the
code expected numerical values. I overrode the functions for the Boolean
metatable to account for this. I also had to exclude the Boolean
metatable from the GenerateTypes helper function, as that was overriding
the Pack/Unpack functions defined in its metatable.

Added Linux bash script to run Lua tests from the command line.

Bug: google/flatbuffers#5379

Tested: Added Lua tests that were failing and are now fixed with the
code changes.

tests/LuaTest.sh

@@ -0,0 +1,22 @@
+#!/bin/bash -eu
+#
+# Copyright 2019 Google Inc. All rights reserved.
+#
+# 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.
+
+pushd "$(dirname $0)" >/dev/null
+test_dir="$(pwd)"
+
+${test_dir}/../flatc --lua -I include_test monster_test.fbs
+
+lua5.3 luatest.lua