LTS: provide a tool for converting "measurement" to "total/total_increasing"

Using a Starline integration.
For a “mileage” sensor earlier I added these lines:

homeassistant:
  customize:
    sensor.auto_xxx_mileage:
      state_class: measurement

since the sensor did not have LTS support natively.
How it was shown on a Statistics graph card:


where only “mean/max/min” options were available (as expected for “measurement”).

A recent PR added a state_class: total_increasing natively.
Then I removed those customize lines from a config.

The sensor has total_increasing now:


After some period of time after HA reboot, on Statistics graph card only “state/sum/change” options became available (as expected for “total_increasing”). But no graph was displayed - probably because there were no “state/sum/change” data in DB yet, and old “mean/max/min” became “meaningless”.

Proposal:
If some sensor’s state_class was changed from “measurement” to “total/total_increasing”:

  1. Create a new issue in “Dev tools → Statistics”.
  2. Provide a possibility to convert old “mean” data into “state” data (“convert” = simply copy these data to a new column).

Although “sum” & “change” data will be still unavailable, this “conversion” will allow to keep old data as statistical.