[ADCP-170] Update Data Importer Documentation for Design Changes

[vaishalimore9]

• Updated use-the-data-importer for new documentation and renamed to data-importer
• data-importer.md contains combined documentation previously under extension and use-the-data-importer.
• Removed old extension documentation and attachments
• Renamed data-importer (import data from file action documentation) to import-data-from-file

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