Define boundary zone from STL-file

[LasNikas]

With this PR, we can pass arbitrary oriented planes (stl-file format) to the InFlow and OutFlow zones.
The reason for this is that for real-world problems one do not need to specify the plane points for the in- and outflow zones.

I basically added a function to calculate the oriented bounding box of an arbitrary oriented plane in space.

An example:

using TrixiParticles

particle_spacing = 0.01
density = 1000.0

open_boundary_layers = 8

filename_plane = "inflow_region_plane"
file_plane = joinpath(expanduser("~/"), "Data", "stl-files", "aorta", filename_plane * ".stl")

filename = "inflow_region"
file = joinpath(expanduser("~/"), "Data", "stl-files", "aorta", filename * ".stl")

geometry_plane = load_geometry(file_plane)

geometry = load_geometry(file)

algorithm = WindingNumberJacobson(; geometry, hierarchical_winding=true)
shape_sampled = ComplexShape(geometry; particle_spacing, density,
                             point_in_geometry_algorithm=algorithm)

flow_direction = TrixiParticles.normalize(sum(geometry_plane.face_normals) /
                                          TrixiParticles.nfaces(geometry_plane))

inflow = InFlow(; plane=geometry_plane, initial_condition=shape_sampled, flow_direction,
                open_boundary_layers, density, particle_spacing)

points = stack(inflow.spanning_set) .+ inflow.zone_origin
points[:, 1] .+= flow_direction*inflow.zone_width

trixi2vtk(points, flow_direction=fill(inflow.flow_direction, 3))