api/views: Create new viewership BigQuery API

[victorges]

This implements the new Viewership V2 API in the analyzer service. It uses bigquery as the
data store and implements all the features proposed for the April project.

This implements DAT-62.

[codecov]

Codecov Report

Merging #121 (2241bd8) into main (dd30988) will increase coverage by 25.63291%.
The diff coverage is 27.27273%.

❗ Current head 2241bd8 differs from pull request most recent head 3d23fdd. Consider uploading reports for the commit 3d23fdd to get more accurate results

@@               Coverage Diff               @@
##           main        #121          +/-   ##
===============================================
+ Coverage      0   25.63291%   +25.63291%     
===============================================
  Files         0           4           +4     
  Lines         0         316         +316     
===============================================
+ Hits          0          81          +81     
- Misses        0         223         +223     
- Partials      0          12          +12     

Impacted Files	Coverage Δ
views/client.go	0.00000% <0.00000%> (ø)
views/prometheus.go	0.00000% <0.00000%> (ø)
views/bigquery.go	44.29530% <44.29530%> (ø)
views/dstorage.go	83.33333% <83.33333%> (ø)

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Impacted Files	Coverage Δ
views/client.go	0.00000% <0.00000%> (ø)
views/prometheus.go	0.00000% <0.00000%> (ø)
views/bigquery.go	44.29530% <44.29530%> (ø)
views/dstorage.go	83.33333% <83.33333%> (ø)

[gioelecerati]

LGTM with comments!