Enhancement: Multiple shared with me tables

We have separated the single table on the shared with me page into up to three different tables:
- pending shares
- accepted shares
- declined shares
By default we show pending and accepted shares. There is navigation in place to switch over from the accepted to the declined shares and the other way around. Pending shares stay visible all the time since it's expected that users take immediate action on pending shares anyway.

https://github.com/owncloud/web/pull/5814
https://github.com/owncloud/web/pull/5177
