Refactor code duplications in dense_kernels tests

[upsj]

Pulled out of #1415, this refactors the dense reference tests to get instantiated for all index types automatically.

[MarcelKoch]

I think this is still too complex to review thoroughly. But I think it might be generally impossible to get this into an easy-to-review state due to the reordering. The only way I can think of is to split this into many more smaller PRs (probably 10 each with 200 LOC changes). But that is unreasonable in our workflow.

So I would be fine merging this, as long as the tests pass.
LGTM, reviewing the commits individually in VSCode makes it bearable.

[pratikvn]

LGTM. Only concern is that the tests that used stride=num_cols were updated to use non-standard stride instead, for example for ELL and Hybrid. But in general, it is probably okay as that is the more general case.

[yhmtsai]

The tests with DenseWithIndexType are in the middle of the test with Dense.
one more commit to reorder them again?

class Dense{};

TYPED_TEST(Dense, ...)

class DenseWithIndexType{};

TYPED_TEST(DenseWithIndexType)

class DenseComplex{};

TYPED_TEST(DenseComplex)

Also make the fixture close to the testing
Ignore this comment. I review the code in the reversed order

[sonarqubecloud]

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0.0% Duplication

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