[software] Add colmap exporter

[simogasp]

Description

Add the exporter to Colmap to convert an AV SfMData into Colmap's format with the relevant folder structure and the txt files for the scene representation.

Features list

• helper functions to extract and convert the scene
• helper functions to test the compatibility of intrinsics
• unit tests
• software to perform the conversion

Implementation remarks

• Since not all the intrinsic types are compatible between the two libraries, the choice has been made to export only those that are compatible and remove the others from the scene.
• An option is added to copy or not the source images into the Colmap destination folder. This enables the user to skip the copy if all the (many) images are in the same folder: since the first step of Colmap's MVS processing is to remove the optical distortion, that command can be run directly on the source folder without an explicit copy.