Add PNG as an additional recorder snapshots format

BUG:435610

User now can use either of JPEG or PNG to record timelapse.

Caveat Emptor:

1. Only active format is going to be exported, so if you recorded your timelapse partly in JPEG and partly in PNG, only frames in current format will be exported.

2. Still no per-document-settings, settings are shared between docs. If you start recording on JPEG, then create a new/open other doc and change format/settings there, they will be applied for all the docs.

Test Plan

• Check if recorder writes as PNG or JPEG when choosing corresponding format
• Check if quality and compression settings are not related
• Check if compression setting work (i.e. affects file size, 0 = large and fast, 5 = small and slow)
• Check if export for both formats work
• Check if profile editor works, may need to reset profile to get rid of hardcoded ".jpg"
• Check if Recorder Manager and it's related functions work

Formalities Checklist

• I confirmed this builds.
• I confirmed Krita ran and the relevant functions work.
• I tested the relevant unit tests and can confirm they are not broken. (If not possible, don't hesitate to ask for help!)
• I made sure my commits build individually and have good descriptions as per KDE guidelines.
• I made sure my code conforms to the standards set in the HACKING file.
• I can confirm the code is licensed and attributed appropriately, and that unattributed code is mine, as per KDE Licensing Policy.