base: port UnixSocket to Windows

This change makes both AF_UNIX and TCP/IP sockets
work on Windows. AF_UNIX support is quite recent and works
only on Windows 10, see [1].
I haven't figured out yet if we should use AF_UNIX or just
a TCP socket on Windows for the IPC layer. In any ase, it feels
like the code can support both with very little efforts as
AF_UNIX doesn't add any extra complexity vs SOCK_STREAM.

[1] https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows/

Bug: 174454879
Change-Id: I9ef645678e8da7c739ccb82e656e49f13441f2a4
diff --git a/.gitignore b/.gitignore
index d50bced..bfcdde9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,15 +12,15 @@
 .project
 .recipe_deps/
 .settings/
-*.iml
-*.pyc
-*.swp
-/bazel-*
-/out*
-TAGS
-/node_modules/
-/compile_commands.json
 .vscode
 *.code-workspace
-/fuzz_out/
+*.iml
+*.pyc
+*.sock
+*.swp
 /bazel-*
+/compile_commands.json
+/fuzz_out/
+/node_modules/
+/out*
+TAGS