Add narratives to sos model configuration

[willu47]

• Narratives are now part of a sos model configuration instead of a model run. This has little effect upon the configuration files, only on how the files are loaded at runtime. The DataInterface remains the same, with the exception of the note below.
• Narratives are stored in the config/narratives folder and contain a list of sector model parameters:

name: technology
description: Describes the evolution of technology
sos_model: energy_water
provides:
  energy_demand:
    - smart_meter_savings
  water_supply:
    - clever_water_meter_savings
    - per_capita_water_demand
variants:
  - name: high_tech_dsm
    description: High penetration of SMART technology on the demand side
    data:
      smart_meter_savings: high_tech_dsm.csv
      clever_water_meter_savings: high_tech_dsm.csv
      per_capita_water_demand: high_tech_dsm.csv

• One small to change to DataInterface - the skip_coords argument has been removed from the read_narrative and read_narratives methods

[codecov[bot]]

Codecov Report

:exclamation: No coverage uploaded for pull request base (develop@ca57052). Click here to learn what that means. The diff coverage is 86.08%.

@@            Coverage Diff             @@
##             develop     #235   +/-   ##
==========================================
  Coverage           ?   78.39%           
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  Files              ?       50           
  Lines              ?     3874           
  Branches           ?      497           
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  Hits               ?     3037           
  Misses             ?      750           
  Partials           ?       87

Flag	Coverage Δ
#javascript	78.39% <86.08%> (?)
#python	84.5% <86.08%> (?)

Impacted Files	Coverage Δ
src/smif/data_layer/database_interface.py	100% <ø> (ø)
src/smif/data_layer/data_interface.py	96.82% <100%> (ø)
src/smif/data_layer/data_handle.py	84.34% <100%> (ø)
src/smif/data_layer/memory_interface.py	96.11% <100%> (ø)
src/smif/data_layer/datafile_interface.py	84.43% <72.34%> (ø)
src/smif/model/sos_model.py	89.03% <86.36%> (ø)

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[willu47]

Further comments from @RoaldL:

• move narrative read and write into sos model read and write calls
• check that sos model reads return a sos model config including narratives