Choose colour for bottom sheet handle

[barry-observation]

Context
A bottom sheet contains a "handle" that shows that you can drag the sheet to make it bigger or smaller. We have been inconsistent in the use of the colour of this handle.

In react-native-components, in bottomSheet.ts, we use theme.color.icon.system.subtle. You could say that this is the wrong type of colour because the handle is not an icon? But it is otherwise unclear whether this is a background colour, a border colour or something else.

In Observation, in bottomSheetStyles, we use theme.color.grey800.

Requirements

• We need to resolve this inconsistency by choosing one colour to use everywhere.
• We can discuss what type of colour this is, so that we can give it the correct semantic name.
• Once done, we need to apply the new colour in:
  • The react-native-components
  • ObsIdentify (should be a matter of updating react-native-components)
  • Observation (update react-native-components and the deprecated bottomSheetStyles)

[lonniebregman]

De kleur moet nog besproken worden met Karel.