WebSockets: Remove unused files

Most of them are because tests not being run on a given platform
or non-existent platform.

Change-Id: I03bd8872b63135ef8e871128f6595f17f0f7e00d
Reviewed-by: Simo Fält <simo.falt@digia.com>
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@digia.com>