Feature request: Delete all tracks

[Nugman]

As a user I would like to be able to delete all uploaded tracks uploaded from my account. Currently it is only possible to delete individual tracks which is a tedious job when there are a couple of 100 tracks to delete.
Usecase: I moved my account to another OBS portal and would like to clear my account on portal.openbikesensor.org to prevent duplicates in case researches aggregate data from different portals.

[gluap]

@Nugman I think this is a valid use case, and it will also make it easier to fulfill GDPR duties of "I want to download/delete all my data".

But be aware that for the research use case the Tracks and Events can be deduplicated based on their hashes (edit: and uniqueness in spacetime in the case of events). In fact we already use this on the portal to prevent duplicate upload of the same track.

[opatut]

This is implemented in next and will be in 0.9.0.