WP 6.6, WP Admin: added GPX Track filtering

Update chart.js and swiper.js to latest versions.
Added Functionality to Admin - GPX-Tracks:
The Map + Track for the selected GPX-Track is shown on the Admin Page. Several filter options (statistics with mean height and speed change, Distance smoothing and simplify.js) were added. The GPX-File is now filtered in the browser and with Button Click "Save" sent as filtered file via http(s) to the server. The server-side (back end) from WP just stores the file now.
Due to the new Functionality several bugs and inconsistencies were removed. Mainly in leafletChartJs-Files and in the AdminSettingsPage.php and admin_settings.php. The function was started with WebAssembly and Rust but later skipped, so the files are still in the repository. The translations in ./languages/*.json were updated for German only.
No need to update to 0.27.0 if 0.26.0 works fine.