fix: Enable loading XSLX with blank rows and sheets for schema and source data

[emanuelaepure10]

It is possible to load XLSX with multiple sheets that may contain blank sheets or rows or cells, both as source data and schema. Wizard: add the last 2 steps in one single step.

ING-4075

[emanuelaepure10]

@florianesser Thank you very much for the comment
it's working indeed like that.
the only think is that you need to be careful to always have skip lines = 0, otherwise one can loose the first line.

@Kate-Lyndegaard for the example from the internal issue

we have 53 instances, as we expected.

My only fear is that

as you have same value for 3 different keywords(I don't know how to call them) from the schema,

and another value for all 3

you are also expecting to see it counted 3 times.

[emanuelaepure10]

@florianesser @Kate-Lyndegaard

I have managed to give the value of the merged cells to all the cells from the merged area. Here is the result.

Please let me know if this is what you expected.

Thank you

[stempler]

LGTM

[florianesser]

@emanuelaepure10 Please rebase the branch to get rid of the merge commit.

[emanuelaepure10]

@florianesser done! Thank you for the feedback :-)

[florianesser]

LGTM