[FEATURE REQUEST] Add ODO reading for vehicle purchase

[staze]

Checklist
Please make sure you have performed the following steps before submitting a new feature request, change [ ] to [x] to mark it as done

• I have read the Contributing Guidelines and Scope and Purpose
• I have searched through existing issues.

Description
There isn't a good way to enter the purchase ODO reading for new/used cars. While I can enter a generic ODO reading, and make the note "Purchased" the distance traveled with the car is still seemingly based on service records even if they predate my ownership of the car.

Would be nice to be able to say "I purchased the car with 240k miles on it, base everything after that".

Acknowledgment

• I acknowledge that LubeLogger is a side project and that development efforts are entirely voluntary. I do not expect the core maintainers to respond to this issue, and I will not hound or chase them regarding this issue or any other issues.