Have fhicl-expand print markings for start and end of inclusion

[knoepfel]

This issue has been migrated from https://cdcvs.fnal.gov/redmine/issues/17933 (FNAL account required)
Originally created by @PetrilloAtWork on 2017-10-17 17:00:13

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The fhicl-expand utility expands inline the #include directives, but it does not say it's doing it.
When debugging some problem, that information might be useful. For example, in the case illustrated in Redmine issue 17893, it would allow to quickly know what file included the FHiCL file in the error message.
This is a request for an option --annotate-include (better name welcome) which would have fhicl-expand insert in the expansion annotations like:

### fhicl-expand: including "/path/to/include1.fcl" from "master.fcl" line 2

and

### fhicl-expand: end of included "/path/to/include1.fcl"

Note that in the use case in Redmine issue 17893, fhicl-dump would not help since it fails parsing and just prints an error message.