add Type property for Latte::View

Summary:
--this way any part interested to know the
real type of Latte::View it can access the
all new type() property

Test Plan:
test view settings that indicate correctly
the panel/dock type

Reviewers: trmdi, Latte Dock

Reviewed By: trmdi

Subscribers: plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D18926