feat: add blas/ext/index-of

[headlessNode]

Progresses #2656.

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This pull request:

• add blas/ext/index-of

Related Issues

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This pull request:

• progresses [RFC]: achieve ndarray API parity with built-in JavaScript arrays  #2656

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Coverage Report

Package	Statements	Branches	Functions	Lines
blas/ext/index-of	$\color{green}582/582$ $\color{green}+100.00\%$	$\color{green}61/61$ $\color{green}+100.00\%$	$\color{green}3/3$ $\color{green}+100.00\%$	$\color{green}582/582$ $\color{green}+100.00\%$

The above coverage report was generated for the changes in this PR.

[kgryte]

Missing out argument validation.

[headlessNode]

Here also, notice the case assign( x, searchElement, out, options ) at L132, and also the case above assign( x, searchElement, out ). Since fromIndex is optional and can be at 3rd place, the issue is that fromIndex can also be ndarrayLike so consider the case assign( x, searchElement, fromIndex_ndarray ). How would we know if that ndarray is a fromIndex or out?

Based on that, I think, the check for out makes sense just before the call to base.

Also, as suggested by you, I tried to comeup with ndarrayLike checks at the top but that also is tricky because we need to first check if fromIndex is actually that or is it out & vice versa. So at the end, we will end up with same amount of ndarraylike checks as we have now.