Apparently the default pasteRules of tiptap interfere with the
pasteRules of a Link (in our case an Embed node). Consider this example:
https://de.wikipedia.org/wiki/Yin_und_Yang
Depending on some random conditions, tiptap might parse the `_und_` to be
italic because it's wrapped with underscores (markdown syntax). The
result is:
https://de.wikipedia.org/wiki/Yin # link
_und_ # italic
Yang # plain text
So let's remove the default pasteRules of `Bold`, `Strike` and `Italic`
marks respectively to prefer our Embeds. Who is copy+pasting from one
tiptap editor to another tiptap editor anyways?
52e0361087