New backfilling system

[KrauseFx]

• [x] Remove everything I back filled (create backup first)
• [x] Add created at and imported at and source column
• [x] Allow drag & drop of raw files into Telegram bot (e.g. RescueTime data, Withings Data,  Health data)
• [x] Store some kind of ID/identifier to only import additional entries, so the user can just periodically drag & drop the most recent export file, and can rely on the bot to do the right thing
• [x] With that, build a system to easily append additional data parsers
• [x] Timestamp of those imports (https://github.com/KrauseFx/FxLifeSheet/issues/80)

[KrauseFx]

Previous issue describing this https://github.com/KrauseFx/FxLifeSheet/issues/105