pkg/references: Replace trace package with custom complex errors

[jeroenrinzema]

Example of the errors which the damon prints on the startup:

Error:
(UnableToResolveFlow) failed to resolve flow 'FetchLatestProject'
        Name: "failed to resolve flow 'FetchLatestProject'"
(UndefinedReference) undefined reference 'user:password' in 'output.Password'
        Reference: {"resource":"user","path":"password"}
        Breakpoint: "output"
        Path: "Password"
(UndefinedReference) undefined reference 'user:password' in 'output.Password'
        Reference: {"resource":"user","path":"password"}
        Breakpoint: "output"
        Path: "Password"
(UndefinedReference) undefined reference 'user:password' in 'output.Password'
        Reference: {"resource":"user","path":"password"}
        Breakpoint: "output"
        Path: "Password"
(UndefinedResource) undefined resource 'user:password' in 'output'
        Reference: {"resource":"user","path":"password"}
        Breakpoint: "output"
        KnownReferences: ["stack","input","error","query","user"]

the repeated UndefinedReference error is related to the references package: that's how the Resolve method resolves the flow. We should probably investigate what happens here.