[multirobot] Spawn multiple robots into Gazebo (#1146)

Moving original files to bringup folder
Adding node for spawning TB3's into Gazebo

nav2_bringup/bringup/launch/spawn_robot_launch.py

+# Copyright (c) 2018 Intel Corporation
+#
+# 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.
+
+import os
+
+from launch import LaunchDescription
+
+import launch.actions
+import launch_ros.actions
+
+def generate_launch_description():
+
+    return LaunchDescription([
+        #TODO(orduno) might not be necessary to have it's own package
+        launch_ros.actions.Node(
+            package='spawn_turtlebot3',
+            node_executable='spawn_turtlebot',
+            output='screen',
+            arguments=[
+                    launch.substitutions.LaunchConfiguration('robot_name'),
+                    launch.substitutions.LaunchConfiguration('robot_name'),
+                    launch.substitutions.LaunchConfiguration('x_pose'),
+                    launch.substitutions.LaunchConfiguration('y_pose'),
+                    launch.substitutions.LaunchConfiguration('z_pose')]),
+    ])

nav2_bringup/spawn_turtlebot3/package.xml

+<?xml version="1.0"?>
+<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
+<package format="3">
+  <name>spawn_turtlebot3</name>
+  <version>0.2.4</version>
+  <description>Package for spawning Turtlebot3 into Gazebo</description>
+  <maintainer email="carlos.orduno@intel.com">lkumarbe</maintainer>
+  <maintainer email="lalit.kumar.begani@intel.com">lkumarbe</maintainer>
+  <license>Apache-2.0</license>
+
+  <buildtool_depend>ament_cmake</buildtool_depend>
+
+  <exec_depend>rclpy</exec_depend>
+  <exec_depend>std_msgs</exec_depend>
+
+  <test_depend>ament_lint_auto</test_depend>
+  <test_depend>ament_lint_common</test_depend>
+  <test_depend>ament_copyright</test_depend>
+  <test_depend>python3-pytest</test_depend>
+
+  <export>
+    <build_type>ament_python</build_type>
+  </export>
+</package>

nav2_bringup/spawn_turtlebot3/setup.cfg

+[develop]
+script-dir=$base/lib/spawn_turtlebot3
+[install]
+install-scripts=$base/lib/spawn_turtlebot3

nav2_bringup/spawn_turtlebot3/setup.py

+from setuptools import setup
+
+PACKAGE_NAME = 'spawn_turtlebot3'
+
+setup(
+    name=PACKAGE_NAME,
+    version='1.0.0',
+    package_dir={'': 'src'},
+    packages=[PACKAGE_NAME],
+    data_files=[
+        ('share/ament_index/resource_index/packages',
+            ['resource/' + PACKAGE_NAME]),
+        ('share/' + PACKAGE_NAME, ['package.xml']),
+    ],
+    install_requires=['setuptools'],
+    zip_safe=True,
+    tests_require=['pytest'],
+    entry_points={
+        'console_scripts': [
+            'spawn_turtlebot = spawn_turtlebot3.spawn_turtlebot:main',
+        ],
+    },
+)