Make AasBuilder build atomic: clone working state, validate references, and add tests#22

Freezor merged 2 commits into12-enable-incremental-submodel-composition-via-addsubmodel-at-any-stage-of-the-build-processFreezor/FluentAAS:12-enable-incremental-submodel-composition-via-addsubmodel-at-any-stage-of-the-build-processfrom

codex/fix-atomicity-in-build-fragment-applicationFreezor/FluentAAS:codex/fix-atomicity-in-build-fragment-applicationCopy head branch name to clipboard