Feature: create/update a View on top of hNhM tables

[marchinho11]

Why?

• hnhm creates a bunch of tables in the DDS layer, to wire them all together you should write SQLs like:

  SELECT
       hub__review.review_sk,
       group__review__review.rating AS review__rating,
       group__review__review.text AS review__text,
       ...
  FROM
       hub__review
  LEFT JOIN
       group__review__review
       ON hub__review.review_sk = group__review__review.review_sk
       AND group__review__review.valid_to = 'infinity'
  ...

What?

• Add a feature to manage a View on top of the hNhM tables
• Now it's easy to select data for the whole entity, no matter how many attributes or groups it contains:

  SELECT
      user_sk,
      name,
      age,
      contacts__mail,
      contacts__phone
  FROM
      entity__user

• This view contains the latest data (for tables in the SCD2 it uses the filter valid_from = 'infinity')

[codecov]

Codecov Report

Merging #11 (01a41a0) into main (5e4bf5a) will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #11      +/-   ##
==========================================
+ Coverage   97.79%   97.87%   +0.07%     
==========================================
  Files          33       23      -10     
  Lines         909      939      +30     
==========================================
+ Hits          889      919      +30     
  Misses         20       20              

Impacted Files	Coverage Δ
hnhm/core/__init__.py	100.00% <ø> (ø)
hnhm/core/attribute.py	100.00% <100.00%> (ø)
hnhm/core/entity.py	100.00% <100.00%> (ø)
hnhm/core/group.py	100.00% <100.00%> (ø)
hnhm/core/migrations.py	100.00% <100.00%> (ø)
hnhm/core/priority.py	100.00% <100.00%> (ø)
hnhm/core/storage.py	100.00% <100.00%> (ø)
hnhm/file_storage.py	100.00% <100.00%> (ø)
hnhm/flow.py	95.65% <100.00%> (ø)
hnhm/hnhm.py	98.79% <100.00%> (+0.11%)	⬆️
... and 5 more