ign to gz : Shared Libs and SDF attributes (systems and plugins)

[methylDragon]

Part of: #698

This tracks the migration effort for the gz -system and plugin shared libs.

This also FOLDS IN THE REMAINING SDF ATTRIBUTE CHANGES!!!

Notes

• They should be merged in topological order
• This should preferably be merged after the macro migration
• ❗❗❗The CMake project name migration has to happen first, since this set of PRs assumes that has already happened (the project names affect certain CMake variables that feed into this, the PR assumes the gz variants for project names are used.)

Libs

• sdformat ign -> gz Shared Lib Migration : sdformat gazebosim/sdformat#1048
• physics ign -> gz Shared Lib Migration : gz-physics gazebosim/gz-physics#356
• sensors ign -> gz Shared Lib Migration : gz-sensors gazebosim/gz-sensors#235
• sim ign -> gz Shared Lib Migration : gz-sim gazebosim/gz-sim#1535
• launch ign -> gz Shared Lib Migration : gz-launch gazebosim/gz-launch#170

Moved

• gazebo.ign, gazebo_plugins.ign
• gz-launch/plugins/: gazebo_factory, gazebo_server, gazebo_gui
  • GazeboGui, GazeboServer, GazeboFactory

Replaced

• executable name='gazebo
• ignition-launch-gazebo-factory
• gazebo-server, gazebo-client
• ...

[methylDragon]

Useful pattern to redirect loads instead of needing symlinks: gazebosim/gz-sim#1527

Here

    // Deprecated: accept ignition-gazebo-prefixed systems
    auto filename = _filename;
    if (filename.find("ignition-gazebo") != std::string::npos)
    {
      filename.replace(0, 15, "gz-sim");
      gzwarn << "Trying to load deprecated plugin [" << _filename
             << "]. Using [" << filename << "] instead." << std::endl;
    }

[methylDragon]

Done!