Constants must be visible in scope to be used

[MattWindsor91]

Right now, there is insufficient scoping policy to prevent, say, something targeting components of module Foraging from picking up the constant Foraging::ObstacleAvoidance::Avoid::turnSpeed. This constant may well be available in the CSP semantics as generated by the current RoboChart generator, but it should be hidden by the scoping rules as it is below Foraging in the component model.