WIP: Add missing 720p and 1080p vertical export profiles, add 8K video export profiles and update social media export presets

[Trainax]

• Created 23.98, 24, 25, 29.97, 50, 59.94 and 60 FPS vertical export profiles for 720p and 1080p videos
• Added all vertical export profiles in the YouTube presets. In particular:
  • 720p vertical export profiles in the YouTube Standard preset
  • 1080p vertical export profiles in the YouTube HD preset
• Add 25 fps vertical export presets to Twitter and Instagram presets, this because there were already the 25 fps horizontal export profiles and 30 fps vertical export profiles, so now there are 25 and 30 fps export profiles both horizontal and vertical.

I think adding vertical export profiles to the YouTube and YouTube HD presets is useful due to the growing popularity of YouTube Shorts where people create short vertical videos

[Trainax]

@jonoomph Sorry to bother you. Can you (or someone else) take a look at this PR to see if it is ok?

If this is merged it would be very useful for creators like me who shoot videos at 25 and/or 50 FPS because we are from a PAL region (50 Hz mains voltage) and lights in videos would flicker if we shot (and edited / exported) at 30 FPS.

Thank you

[Trainax]

Hello everyone.

Since this PR hasn't been merged yet and YouTube has added 8K recommended video bitrates in their guide I thought it would also be useful to create profiles for 8K resolution and create a YouTube export preset for this resolution. Let me know what you think

The bitrate used for 8K videos are:

	Low	Med	High
Video bitrate	160 Mb/s	200 Mb/s	240 Mb/s
Audio bitrate	128 kb/s	256 kb/s	320 kb/s

[jonoomph]

Thanks again for all the work on this PR! I am actually in the process of replacing ALL profiles in OpenShot - which conflicts with this one at the moment. Bottom line, all of these profiles will be included in OpenShot shortly - one way or another, lol. I'll update this ticket again shortly.

[jonoomph]

LGTM! I'm going to merge this into develop first, and then I'll reconcile changes with my new profiles branch. Thanks for the work on this one! 👍