Loading of XLSX files with more than one headline does not work correctly

[numeredev]

DESCRIPTION

Describe the bug Loading an XLSX file, which contains more than one headline converts everything to string columns. Might need a fix like in #45, where we used some kind of a heuristic.

To Reproduce Steps to reproduce the behavior:

1. Load the file xlsx-8_shortVersion.xlsx
2. Open the loaded file in the table viewer
3. See error

Expected behavior The first two rows should be used as table headlines instead of leaking into the table columns.

Screenshots If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: 10x64
• Version v1.1.5.2303

Additional context Add any other context about the problem here.

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DEVS' SECTION

ANALYSIS

The issue is in fact identical to the one solved within #45. Futhermore, the same problem occurs with ODS files.

IMPLEMENTATION STEPS

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DOCUMENTATION STEPS

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PULL REQUEST

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