bpf: add support for new fields in BPF_PROG_TEST_RUN

bpf: add support for new fields in BPF_PROG_TEST_RUN

* bpf_attr.h (struct BPF_PROG_TEST_RUN_struct): Add ctx_size_in,
ctx_size_out, ctx_in, and ctx_out fields.
* bpf.c (BEGIN_BPF_CMD_DECODER(BPF_PROG_TEST_RUN)): Decode these fields
introduced by Linux kernel commit v5.2-rc1~133^2~193^2~6.
* tests/bpf.c (BPF_PROG_TEST_RUN_checks): Check it.