Add pre-analysis hook to new workflow

[sambles]

The pre-analysis hook needs integration with the new platform

The distributed worker is calling the oasislmf manager function OasisManager().generate_files(**params) to create the oasis run files. This doesn't include the pre-analysis hook step.

The older worker used something equivalent to OasisManager().generate_oasis_files(**params) from oasislmf/computation/run/generate_files.py which conditionally calls ExposurePreAnalysis.

Swapping one for the other might be problematic, since at this point in the execution the distributed worker has already generated lookup results with the unmodified location file.

An optional step or task is needed before the sub-task(s) prepare_keys_file_chunk generates lookup results

[sambles]

Two options for adding:

1. add new optional task to run pre-analysis hook before keys lookup. Then push the modified location file back in the server's storage and continue with lookup stage.

2. Run each pre-analysis as a partial step before running the lookup chunk. Combine all partial location data back into a single file and push that into sever storage once the all lookup's have been processed.

modified exposure storage
a) Copy an existing portfolio and store the modified files under a new portfolio id, have both portfolio links under an analysis object.

b) Add new endpoints to all portfolio's for modified file storage.