Resource manager respecting processor's moduledir

[kba]

This implements proper support for processor's moduledir:

• Processors have a new CLI option --dump-module-dir that prints the moduledir of the processor
• When downloading a model
  • unless --location is explicitly overridden, resmgr will inspect the resource_location in a processor's ocrd-tool.json and select the first one
  • if the location is module, will get the directory via --dump-module-dir
• For list-installed, looks up the directory via --dump-module-dir and will look in it as well.

This also removes the find_resources method which is mostly redundant with list-available

It is a draft because I introduced a bug where downloading a model duplicates all the entries for that executable. Will have to debug this further tomorrow.

[kba]

It is a draft because I introduced a bug where downloading a model duplicates all the entries for that executable. Will have to debug this further tomorrow.

Debugged and ready to go.