introducing export-ignore directive for all files to make github-generated tarballs emtpy

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 42.71%. Comparing base (ebee9df) to head (ddc8c61).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1774 +/- ## ======================================= Coverage 42.71% 42.71% ======================================= Files 361 361 Lines 97333 97333 Branches 19929 19929 ======================================= Hits 41577 41577 Misses 55756 55756 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[GillesDuvert]

@slayoo you can merge I presume?

[slayoo]

thanks, let's try it!