ENVI is a popular file format for multi spectral images.
Images coming from our potentially new IMEC camera will be saved in this format.

More information
https://www.harrisgeospatial.com/docs/ENVIHeaderFiles.html on the format:

For python the spectral python (SPy) module provides read/write methods for ENVI files and contains some multi-spectral algorithms.

In this bug, check if we should use the SPy image class for processing in our MSI module. This would mean significant porting necessities, so if we do it it should pay of.

If not, I propose to use the SPy reader/writer and an adapter to be able to process ENVI files in the future (see T19712)