fix: Set Tableau URLs (base + API) via config

[alevene]

Summary of Changes

When executing the Tableau extractor in different environments (development, production, etc), we saw the need to have different URLs and protocols depending on connectivity. For example, our airflow server that runs the extractor routes to the Tableau server via port 80 and a specific IP address.
To allow for the most configurability, this PR opens up 2 values:

• API_BASE_URL - Protocol+Host for API calls
• TABLEAU_BASE_URL - Protocol+Host for links on the Dashboard Detail page (eg. "Open Dashboard" button)

TABLEAU_HOST has been removed in favor of these.

Tests

Added new configs to tests.

Documentation

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[feng-tao]

lgtm, thanks