Merge branch 'export' into 'master'

Export activities time (TXT/CSV)

This MR adds an export button and dialog to the reports UI. Reports can be simple (just the activity name and time) or detailed (everything except the IDs). They can also be in TXT or CSV format. I'm leaving out PDF for a future MR.

closes #2

See merge request !9
1 job for master in 49 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Flatpak
passed #251953
flatpak

00:00:49