Add Support for Struct Conversion when reading Arrow data

[kronsbein]

What changes were proposed in this pull request?

This PR adds support for struct conversion when reading Arrow data

Why are the changes needed?

Resolves #114

Does this PR introduce any user-facing change?

Additional functionality when reading Arrow data

How was this patch tested?

By extending existing test case TestReadArrowRecord

[haoxins]

maybe we can now use

for j := range data.NumField() {

:)

[kronsbein]

Sure, thank you for your review!

[grundprinzip]

Can you please add an integration test with something like this:

select named_struct('a', 1, 'b', 2, 'c', cast(10.32 as double), 'e', array(1,2,3,4))

[kronsbein]

I added an integration test under internal/tests/integration/sql_test.go. Not exactly sure, if this is the right place, please let me know if I should move it somewhere else.

[grundprinzip]

Thanks for the contribution, merging to master.