Kokkos impl potential and integrator

[galjos]

Kokkos implementation of:

• brute force potential (Wolf & LJ-12-6)
• velocity-verlet integrator
• adapted tests

Additionally, a custom profiler "timings" was added to make function call time visible.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 64.85320% with 407 lines in your changes are missing coverage. Please review.

Project coverage is 77.16%. Comparing base (9aca8bc) to head (3756038).

Files	Patch %	Lines
src/engine/engineOutput.cpp	22.68%	75 Missing :warning:
src/output/timingsOutput.cpp	0.00%	62 Missing :warning:
src/setup/outputFilesSetup.cpp	0.00%	43 Missing :warning:
src/timings/timer.cpp	32.69%	35 Missing :warning:
src/thermostat/noseHooverThermostat.cpp	0.00%	33 Missing :warning:
src/engine/ringPolymerEngine.cpp	0.00%	27 Missing :warning:
include/engine/engineOutput.hpp	13.33%	13 Missing :warning:
src/timings/globalTimer.cpp	0.00%	13 Missing :warning:
src/settings/outputFileSettings.cpp	0.00%	12 Missing :warning:
src/thermostat/velocityRescalingThermostat.cpp	0.00%	11 Missing :warning:
... and 16 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #50 +/- ## ========================================== - Coverage 78.41% 77.16% -1.26% ========================================== Files 260 266 +6 Lines 6538 7143 +605 Branches 2435 2617 +182 ========================================== + Hits 5127 5512 +385 - Misses 1391 1611 +220 Partials 20 20 ```

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