feat(Gate): add endpoint for confidence criteria stats

[nicoprow]

Description

This pull request add an endpoint for the gate showing aggregation stats for confidence criteria:

• numberOfBusinessPartnersAverage: average number of how many sharing members have shared the same business partners
• unqiueTotal: number of business partners that are unique to the sharing members
• sharedByOwnerTotal: number of business partners that have been shared by the owning sharing member
• checkedByExternalDataSourceTotal: number of business partners that have been validated against an external data source
• confidenceLevelAverage : average confidence level among business partner records in the gate

Pre-review checks

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• DEPENDENCIES are up-to-date. Dash license tool. Committers can open IP issues for restricted libs.
• Copyright and license header are present on all affected files