Changes

• Add UQ executable to cmake
• Refactors various setup steps out of purify main and into separate functions so that they can be shared with UQ
• Calculates likelihood / prior terms assuming they are L2 and L1 norms (will need update when pytorch models are in place)

Currently needs

• I think sigma can be derived from the purify config parameters so that should be updated
• We need some purify config files to test the UQ and purify apps with to make sure nothing is breaking
• There are two paths for the setup, one using a purify config file and one based on the algo_factory test case. This is so there's something I can run this with and check that the app is doing something sensible in lieu of a purify config file but it should be taken out later.
• Some appropriate tests need to be devised.

Issues
Replacing the line:
const VectorC wavelet_rep = wavelet_operator->adjoint() * image;
in UQ with
const auto wavelet_rep = wavelet_operator->adjoint() * image;
causes a seg-fault, although I don't know why yet. The inferred type of wavelet_rep is AppliedFunction, and in the next line when we call the sum and things are evaluated we get a seg-fault.