Implement a first version of a proper build ID computation.
Implement a first version of a proper build ID computation.

Currently, the build ID is built from a few options that are not strictly necessary to be included (build flags and options) - it would be sufficient to just include the build settings introduced by the selected build type (and would reduce the number of build cache folders).

grogancolin/dub,D-Programming-Language/dub,Geod24/dub,jeanbaptistelab/dub,gedaiu/dub,dreamsxin/dub,y12uc231/dub,rjframe/dub,xentec/dub,Flamaros/dub,jelmansouri/dub,Abscissa/dub,alexeibs/dub,nazriel/dub,p0nce/dub,Abscissa/dub-data-mod,schuetzm/dub