Fix cmake issues with external libraries

[ruffsl]

This fixes several cmake issues when using external libraries

• Don't assume opengv headers are installed system wide
• Include missing DBoW2 headers

[ToniRV]

@ruffsl I don't see why you need to put DBoW2 include dirs here, this should be already done when calling DBoW2::DBoW2 in target_link_libraries (are you using DBoW2 headers through Kimera?).

[ruffsl]

I don't think that interface is working as you expect. My hunch is that the project was relying on and on finding the headers via the system global paths given the sketchy *sudo* make install

Kimera-VIO/Dockerfile_18_04

Lines 68 to 74 in a913c97

	# Install DBoW2
	RUN git clone https://github.com/dorian3d/DBoW2.git
	RUN cd DBoW2 && \
	mkdir build && \
	cd build && \
	cmake .. && \
	make -j$(nproc) install

or depended on a erroneous limitation in legacy catkin for non-isolated devel space builds:

https://answers.ros.org/question/320613/catkin_make-vs-catkin_make_isolated-which-is-preferred/?answer=320706#post-id-320706

When using current build tools, each package must explicitly declare it's install steps given the use of sanitary/isolated builds. Thus every downstream package must similarly explicitly import the resources they need, as no cmake context it implicitly shared across workspace packages.