Handle precise orbits

[lupemba]

• Create a precise orbit data struct in the SARprocessing Module
• Create a loader for sentinel 1 precise orbits.
• Create a function create a orbit interpolate function based on the precise orbits data

[lupemba]

• For inspiration, see ´Precise_orbit(path,t_0)´ in https://github.com/lupemba/syntese/blob/master/ToolBox/src/Load.jl -- I think we should drop the t_0 input. -- Make a ´struct´ named OrbitState with the fields; time, position, and velocity. -- Make the function return an array of OrbitState, ´Array{OrbitState}´
• Information about precise orbits. https://sentinels.copernicus.eu/web/sentinel/-/copernicus-sentinel-1a-and-1b-precise-orbital-products-currently-available-for-the-entire-mission.

[igaszczesniak]

The orbit interpolation function should be another issue.