Fix Windows build of Jaeger tests

[MrAlias]

The Jaeger tests use the low-level syscall package. The Windows specific function called in that package has a different function signature than the unix version. Add a windows specific file using the build flags to isolate this OS specific functionality.

I'm able to verify this fixes the compilation of the testing package and the test failure on a Windows system:

go test -timeout 30s -short ./exporters/trace/jaeger/...
ok  	go.opentelemetry.io/otel/exporters/trace/jaeger	2.906s
?   	go.opentelemetry.io/otel/exporters/trace/jaeger/internal/gen-go/jaeger	[no test files]
?   	go.opentelemetry.io/otel/exporters/trace/jaeger/internal/gen-go/jaeger/collector-remote	[no test files]

Resolves #1576

[codecov]

Codecov Report

Merging #1577 (3b56a12) into main (4a163be) will decrease coverage by 0.0%.
The diff coverage is 44.4%.

@@           Coverage Diff           @@
##            main   #1577     +/-   ##
=======================================
- Coverage   78.0%   78.0%   -0.1%     
=======================================
  Files        127     128      +1     
  Lines       6597    6606      +9     
=======================================
+ Hits        5151    5155      +4     
- Misses      1201    1204      +3     
- Partials     245     247      +2     

Impacted Files	Coverage Δ
exporters/trace/jaeger/assertsocketbuffersize.go	44.4% <44.4%> (ø)

[MrAlias]

Looking further into the error message from the actual test run, it looks like this will always fail on Windows. The network file descriptor is not available from the connection on Windows. A dup method still needs to be implemented for the netFD on Windows.

https://github.com/golang/go/blob/6cc8aa7ece96aca282db19f08aa5c98ed13695d9/src/net/fd_windows.go#L175-L178

I'm going to updated this to return just return true and add a comment.