[Auditbeat] Package: Close librpm handle

[cwurm]

Closes the librpm handle we dlopen() when the dataset is closed.

Lots of lines changed because I expanded and renamed cFun to be librpm, but the important part is saving the handle as librpm.handle and closing it in the new closeDataset() function.

Following #12168 this further reduces the leftover memory Valgrind reports (running valgrind --leak-check=full --show-leak-kinds=all ./auditbeat -e -d "*"):

Before

==8072== LEAK SUMMARY:
==8072==    definitely lost: 116 bytes in 1 blocks
==8072==    indirectly lost: 0 bytes in 0 blocks
==8072==      possibly lost: 3,336 bytes in 10 blocks
==8072==    still reachable: 36,492 bytes in 98 blocks
==8072==         suppressed: 0 bytes in 0 blocks

After

==7839== LEAK SUMMARY:
==7839==    definitely lost: 403 bytes in 3 blocks
==7839==    indirectly lost: 0 bytes in 0 blocks
==7839==      possibly lost: 2,844 bytes in 9 blocks
==7839==    still reachable: 16,840 bytes in 46 blocks
==7839==         suppressed: 0 bytes in 0 blocks

I'm not sure where the remainder is coming from, or if those numbers are even valid given that Valgrind is not really compatible with Golang.

[elasticmachine]

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