[FEATURE] [redditpost] Optionally publish posts in announcement channels

[tigattack]

Describe the feature you'd like

It'd be great to have the option to publish posts made in an announcement channel with the redditpost cog.

Additional context

None.

[flaree]

I'll implement this once Red 3.5 is released, all my cogs are currently feature locked until they support the next release.

[tigattack]

No problem, thanks!

[flaree]

Added in latest commit, thanks for the suggestion.

You can enable it with [p]redditpost publish

[tigattack]

Thanks!