[rviz_tactile_plugins] Add possibility to lock the range

[guihomework]

In certain cases, it could be interesting to artificially adapt the color range displaying taxels in the tactile_state_display plugin so that small changes in the data are visible.
for instance, with a very small range in the range property, one can get very small values light-up the taxel in all color range. However the plugin auto-updates the range min/max so that any higher value changes the range.

A property checkbox locking the range could help in keeping user-selected range.
I think the property should be per sensor, but it is also true that opening all sensors and checking a checkbox for each of them is cumbersome, so a secondary global checkbox enabling/disabling all the locking could be helpful too.

A PR will be provided immediately, adding the checkbox to each sensor (not yet the global one)