Teslafi Import after first Teslamate Datapoint

[jonchen727]

What would you like to be added:
Allow teslamate to fill gaps in data from a teslafi/other logger import

Why is this needed:
Fill missing when teslamate was down from redundant sources

Additional context:

[BabyYeggie]

For further information, this is due to the unique index used in the database. Attempts to import data before/between drives/charges/etc. Attempts to insert data will have the following error:

ERROR: duplicate key value violates unique constraint "positions_pkey"
DETAIL: Key (id)=(xxxx) already exists.