Add model.sdf files for robot models with a thermal camera

[iche033]

This pull request is a proposal to keep track of the model.sdf files for:

• MARBLE_HUSKY_SENSOR_CONFIG_3
• MARBLE_HUSKY_SENSOR_CONFIG_4
• MARBLE_HD2_SENSOR_CONFIG_3
• MARBLE_HD2_SENSOR_CONFIG_4
• CERBERUS_M100_SENSOR_CONFIG_2

motivated by issue #821

Currently the marble sensor config 3 and 4 models are equivalent to the sensor config 1 and 2 models + a thermal camera., and the cerberus sensor config 2 is a copy of config 1 with a thermal camera. They currently do not have their model.sdf files in the subt repo. Issue #812 due to us overriding the thermal changes in the model.sdfs on Fuel with changes from #798

This is a proposal to keep a reference copy in the repo so we can track its changes better with git. Note this may help with version control but adds extra maintenance effort.

Signed-off-by: Ian Chen [email protected]

[peci1]

Also add Cerberus M100 SC2.

[iche033]

added cerberus m100 sensor config 2 in 9758867

[adlarkin]

@iche033 I made some minor updates in b19bab4 that make it easier to compare the diff between MARBLE_HD2_SENSOR_CONFIG_1 and MARBLE_HD2_SENSOR_CONFIG_3.