Add api route to only list your own matches

[jannislehmann]

We want to add an API route, which only shows ones own match results and whether the player's team won.

It is still to be decided, whether we want to pass the playerId / steamId in the request or whether this should be extracted from the authentication token. The second solution would require a lot of changes in the app.

Afterwards, we can remove / fix issue #69