Clean URL in announcement share link button

[petersalomonsen]

The current button for sharing announcements gives a link like this:

https://near.org/s/p?a=webassemblymusic.community.devhub.near&b=112244156

Which will point you directly to the post at near.org without the context of DevHUB or the community, as we can see from the screenshot

The preferred solution would be a cleaner URL, with the community in the path, and that the community page is shown and the post is scrolled into the view:

The URL should then be something like: https://devhub.near.page/community/webassemblymusic/announcements?accountId=webassemblymusic.community.devhub.near&blockHeight=112244156

[petersalomonsen]

See preview videos in #907