Migration to version 16.0

[sbidoul]

Todo

https://github.com/OCA/maintainer-tools/wiki/Migration-to-version-16.0

Modules to migrate

• connector_importer - By @simahawk - [16.0] connector_importer: migrate to v16 #106
• connector_importer_product - By @simahawk - [16.0][MIG] connector_importer_product #129
• connector_importer_source_sftp

Missing module? Check https://github.com/OCA/maintainer-tools/wiki/%5BFAQ%5D-Missing-modules-in-migration-issue-list