sys: util: Add GET_ARGS_FIRST_N to get the first N of the args

[soburi]

Gets the specified number of elements from the beginning of the list.
This is the symmetircal operation as GET_ARGS_LESS_N.

[soburi]

I think the implementation is straightforward.
I'd be happy to hear any comments on whether you think the name is preferable.

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[yperess]

I would prefer if you could demonstrate a use in tree. Why do we need this?

[soburi]

@yperess

I would prefer if you could demonstrate a use in tree. Why do we need this?

This is a basic list operation, so it can be used in various ways, but the most typical use is to extract a sublist from a list.
I've cut it out into this PR because it's an easy chunk to review.

https://github.com/zephyrproject-rtos/zephyr/pull/87595/files#diff-d5eb7802a9e704874c7a8b2a39bcc2c06899d6f59fd169555f9f2dd1f7b8cd93R17-R18

#define DT_MAP_HELPER_DO_ARGS_RANGE(start, len, ...)                                               \
        GET_ARGS_FIRST_N(len, GET_ARGS_LESS_N(start, __VA_ARGS__))
#define NUM_0to7 0, 1, 2, 3, 4, 5, 6, 7

DT_MAP_HELPER_DO_ARGS_RANGE(4, 2, NUM_0to7) // 4, 5

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