remove CONST_VECTOR from OnePositionParameter

[BrianMarre]

change from old CONST_VECTOR for specifying the initial particle position in the template parameter for the OnePosition startPosition functor to the new constexpr float3_X compile time specification.

This breaks old setups, trying to compile a setup using CONST_VECTOR will give the following error:

... picongpu/include/picongpu/../picongpu/particles/startPosition/OnePositionImpl.hpp(45): error: a nonstatic member reference must be relative to a specific object
              constexpr auto initialPosition = T_ParamClass::inCellOffset;

To update a setup, replace in particle.param your definition of the OnePositionParam, something like the following,

CONST_VECTOR(
    float_X,
    3,
    InCellOffset,
    /* each x, y, z in-cell position component in range [0.0, 1.0) */
    0.0,
    0.0,
    0.0);
struct OnePositionParam
{
    static constexpr uint32_t numParticlesPerCell = TYPICAL_PARTICLES_PER_CELL;

    const InCellOffset_t inCellOffset;
};

with an updated version along the lines of this

struct OnePositionParam
{
    static constexpr uint32_t numParticlesPerCell = TYPICAL_PARTICLES_PER_CELL;

    static constexpr auto inCellOffset = float3_X(0., 0., 0.);
};

[BrianMarre]

@psychocoderHPC please, restart CI, CI job failed due docker daemon not answering