Use precise orbit files for establishing grid of ECEF sensor position matching S2 grid (LIA)

Knowing which input S1 files to download in order to generate grid of XYZ sensor positions (aligned on S2 grid) can be a bit tricky:

• S1 product footprints seldom cover S2 tiles -- hence S1Tiling, that concats data from 2 S1 products
• We have no documentation that tells how wide is the Orbit State Vector (OSV) series found in S1 products
• Downloading one S1 product just for its embedded orbit information is a bit overkill.

Instead we should use precise orbit files.

Notes: (non-issues)

• As we typically expect the LIA maps to be computed beforehand, we don't need to wait for 3 days before obtaining orbit data for a given pair of S2 tile + relative-orbit-id. We can just use any orbit data published long before.
• OTB 9 (/SARDEMProjection2's) SarSensorModel can compute sensor positions from the precise orbit data -- we don't need extra data like GCPs, slantRangeTime...

The resolution of this issue can be decomposed as such:

• Fetch Precise Orbit Files from an/the official provider
  • https://github.com/scottstanie/sentineleof may help
• Change download routine to support this new source of data
• Create a new OTB application
  • that reuses SARDEMProjection2 code related to -withxyz, -withsatpos and that supports DEM in any spatial reference
  • that decodes OSV data from EOF files to construct FastSarSensorModel accordingly
• Adapt the LIA ComputeGroundAndSatPositionsOnDEM step to use the new OTB application