Add file validator/dispatcher component

[timcanham]

When sending files to a flight system, especially long latency deep=space missions, it is useful to validate files and do autonomous actions without ground-in-the-loop. This proposal is to add a component that does validation and dispatches files to components that need them.

Ths would entail:

1. Add a port to Svc/FileUplink that emits a file name when uplink is complete.
2. Implement a new component that has an input port from 1).
3. Implement "validate" and "execute" output ports that have a file name for downstream components.
4. The component will have a user-supplied table that maps filename extensions to the "validate" and "execute" ports.

This is a tinker-toy component that will implement part of the chain for auto-validating and auto-executing uplinked files.

[thomas-bc]

For awareness: CFDP supports "User Message", which is basically arbitrary metadata sent alongside a file transaction. Sounds like this could be leveraged in many ways, for example "this is an auto-run sequence" etc