homogeneous denoising

[vincelhx]

No description provided.

[agrouaze]

The idea is to make sure the denoising strategy is implemented in the same way for RCM / S-1 and RS2.
In particular, for RCM it is possible to access to already denoised Digital Numbers which is not currently the case for the 2 other missions.
evolution should be done for:

• code S1 and RS2 with homogeneous code for the denoising of the three sensors  #246
• documentation

[vincelhx]

I add :

• for RS2, search noiseSubtractionPerformed information in SCF products (cf p41 in https://earth.esa.int/eogateway/documents/20142/0/Radarsat-2-Product-Format-Definition.pdf/1ca0cf1e-5a15-a29b-6187-9e5cb1650048)
  will be handle with add information of noiseSubtractionPerformed xradarsat2#34

• addapt code in xsar and set warning if noiseSubtractionPerformed = True
  Note : at this date, no product found with 'true'