Handle is kind of a mess at the moment, this is a first step towards cleaning it up: 1. We had two functions called getDalfDependencies with one wrapping the other. This PR merges them into one to make this less confusing. 2. buildDar called runAction a bunch of times directly and via other functions. This PR switches it to use a single call to runAction. 3. The logic for turning a Maybe into an `ExceptT [FileDiagnostic]` was duplicated in various places. This PR factor out the logic into a single function. There is certainly more cleanup to be done (e.g., I don’t think ExceptT buys us anything here, that module should probably die completely with the logic being moved to other modules, …) but I’d like to do it incrementally.