Extract some code out of pipeline executables to reusable modules (part 2)

[p12tic]

This PR moves code out of cameraInit executable to aliceVision libraries that can be linked into other executables which in turn allows code reuse.

The Extract ... commits only move code around reindenting it to 4-space indents in the process.

The last commit changes how warning reporting is done in cameraInit. This can be potentially be reused in external code now too.

In this PR 3 race conditions have been identified and fixed.

This PR is a followup to https://github.com/alicevision/AliceVision/pull/1270 and is filled separately because it solves a more complicated case.