Improve profile page

Here's a bunch of visual & functional improvements to the profile page!

• Hide the extra notes separator when the notes field isn't visible (like when viewing your own account)
• Change the account statistics to chips
• Add different tabs for Posts, Replies, and Media (we don't have a gallery view yet, it just shows posts with media attachments). I'm not super sold on using a QQC2 TabBar here, suggestions appreciated.
• Add a "Hide boosts" switch to hide boosts on the Posts or Replies page. I have always wanted this in a Mastodon client, especially when finding my own posts under the piles of boosts I do everyday 😛

The account model is tweaked a bit to expose a bunch of tweakable values, a lot of it is already used (exclude replies, boosts, etc) in QML but in the future it can support stuff like searching for featured tags on someone's profile. The "Hide Boosts" switch will look lonely there for now...

Before

After