File upload review and update

[jdavid]

After the latest review, done while adding support for the sommer data logger.

Todo:

• Add more tests, e.g for Eddypro upload.
• Move eton2 data to ClickHouse, then drop support for PostgreSQL in import_file command
• Upload data files using a new API endpoint, like done for Eddypro data.
• Then the import_file command will use the API instead of importing directly, move the command to the client.
• Move Eddypro data to ClickHouse.
• Add new table in ClickHouse with one row per file with all the metadata. Data rows will have a foreign key to this table. It should be possible to reconstruct the source files from the database.