refactor(libsinsp): split `sinsp_fdtable` and `sinsp_fdinfo` #2952

Job	Run time
paths-filter	4s
build-drivers-s390x 😁 (system_deps)	1s
test-drivers-amd64 😇 (bundled_deps)	3s
test-drivers-arm64 😇 (bundled_deps)	3s
test-scap-amd64 😆 (bundled_deps)	1s
test-drivers-ppc64le 😁 (system_deps,custom node)	0s
build-modern-bpf-skeleton	0s
test-scap-arm64 😆 (bundled_deps)	3s
kernel-tests-dev	0s
build-scap-open-w-extern-bpf-skeleton	0s
kernel-tests-pr-info-upload	0s
	15s

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