Open Lemmy content from Safari in Mlem via Share extension

[nicfab]

Introduction

I am testing MLem.
Congratulations on the project.

Requirements

I suggest improving the app by adding the share feature, so it will be possible - for example - to share content from Safari directly to MLem.

[ShadowJonathan]

This probably intersects with https://github.com/buresdv/Mlem/issues/104

Also, this intersects with the default account feature (https://github.com/buresdv/Mlem/issues/96) in a way we need to think about; if the app is closed, are we going to open the link in the default account, or the last-opened account? Wouldn't it be easier to make the last-opened account the "default" one?