[2022 M4] Improve battery model (non-constant discharge rates)

[marcoag]

This issue is to discuss and track the progress on Improving the battery model being used at the time of writing.

Discussion:

The Tethys model currently uses the gazebo battery plugin that implements a linear battery model. The idea is to improve the this plugin and its use by the Tethys model in order to make a more accurate use of the battery charge by adding ways to have non-constant discharge rates.

1. Dynamic addition and removal of power consumers.

After discussing this will be done through components, as follows:

• A plugin can sign up as a battery consumer by creating this component with the value of the power load.
• This power load will be added to the battery model.
• Make sure the power load is removed when the plugin is not there anymore.

2. Add topics support

3. Add topics support

[caguero]

See gazebosim/gz-sim#1811