Merge branch 'sockmap: add sockmap support for unix stream socket'

Jiang Wang says:

====================

This patch series add support for unix stream type
for sockmap. Sockmap already supports TCP, UDP,
unix dgram types. The unix stream support is similar
to unix dgram.

Also add selftests for unix stream type in sockmap tests.
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Signed-off-by: Andrii Nakryiko <andrii@kernel.org>