Improve XRT test suite

[TristanLaan]

The test script currently only tests a limited set of inputs which sometimes results in bugs being merged into the project without us realizing. The script is also turning quite large and crashes on the first error. We should look into switching to a unit test framework like GoogleTest.

Improvements

• [ ] Test all data types and multiple data sizes
• [ ] Use different types of buffers for all tests (unaligned, aligned, bo buffer)
• [x] Continue testing on error
• [x] Switch to unit test framework (i.e. GoogleTest)

[quetric]

WIP switch to gtest in #138