refactor isApproxSame and checkScalars interface

[tarun-mitruka]

Currently, there is an implementation of checkScalars from #193 and there is an existing isApproxSame functionality in testhelpers.hh.

Refactoring of the interface is needed which includes only one check function that is able to switch between checkScalars and isApproxSame and perform the correct check irrespective of the type (int, double, Eigen::VectorXd,...).

Moreover, the TestSuiteType can be also be passed as the error message is most of the time of the following format in the whole test suite.

t.check(val == expectedVal) << std::setprecision(16) << "Incorrect -> Expected:\t" << expectedVal << " Actual:\t" << val << messageIfFailed;