Rename overpass/* to overpass/*.overpassql

[FloEdelmann]

*.overpassql is now the recommended file extension for Overpass QL: OSM Wiki: Overpass QL § File extension
(Disclaimer: I added that section after some discussion.)

I propose to rename all Overpass QL files in this repo to *.overpassql for consistency.

Context: GitHub's syntax highlighting engine requires that 200 repositories use the same file extension before they consider supporting that syntax and file extension: github-linguist/linguist#5890

[jbelien]

Thanks a lot @FloEdelmann ! 👍
I saw a similar PR in one other of the repositories I manage. 😄
Excellent idea IMHO, I'll make sure I apply this new "logic" to all the repositories that I manage.

[FloEdelmann]

Nice, thank you! Please mention me in the PRs or commits if I didn't already open an issue in that repo yet, so that I can keep track of the repos using the new file extension 🙂

[FloEdelmann]

Thanks for renaming and pinging me 😊

[jbelien]

All 48 repositories of the EqualStreetNames project have been updated! ✅

[FloEdelmann]

Oh wow, that's so many!