strparser: Add read_sock callback

strparser: Add read_sock callback

[ Upstream commit 0532a79efd68a4d9686b0385e4993af4b130ff82 ]

Added a new read_sock handler, allowing users to customize read operations
instead of relying on the native socket's read_sock.

Signed-off-by: Jiayuan Chen <mrpre@163.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://patch.msgid.link/20250122100917.49845-2-mrpre@163.com
Stable-dep-of: 36b62df5683c ("bpf: Fix wrong copied_seq calculation")
Signed-off-by: Sasha Levin <sashal@kernel.org>