Add support for CUDA in CI

[shrijitsingh99]

Updated Dockerfile for CUDA 10.2 support
Updated Eigen version to resolve CUDA conflict
Updated GCC version to resolved build errors in GPU module

[kunaltyagi]

• The CUDA version should also be updated in the CI which generates (and overrides) the version in the file
• Eigen3 is being installed regardless
• If default gcc-x, x> 7, no need to install gcc-7

[shrijitsingh99]

Should I also bump the librealsense version while I am at it?

[SergioRAgostinho]

Should I also bump the librealsense version while I am at it?

Ideally, only for the 20.04 build I would say. 16.04 addresses the lowest possible versions and 20.04 the highest. Thoughts?

[shrijitsingh99]

Ideally, only for the 20.04 build I would say. 16.04 addresses the lowest possible versions and 20.04 the highest. Thoughts?

Sounds good, Tracking these versions as you mentioned on #4099, would allow us to identify and bump versions accordingly, maybe in every release, not sure.

[shrijitsingh99]

Will bump real sense version in a seperate PR.

[kunaltyagi]

LGTM, but not to merge

This actually paints the CI red, so adding more PR to resolve the issues would be preferred (rather than changes in this one)

[kunaltyagi]

Oh, and the docker images should be updated separate to the CI. That actually allows the pipeline to update them.

[shrijitsingh99]

Okay, so let me split this into 3 PR's then:

1. Add clang CI to Ubuntu 18
2. Update Docker image
3. Integrate GPU builds with a new image (This PR)
   We can merge them in the order specified. Does that sound good?

[kunaltyagi]

We can merge them in the order specified

Number 2 has a very high chance of being 1st to be accepted

[shrijitsingh99]

This should be good to do now. Have rebased with master.