Add Windows sign.sh retry and check curl rc

[andrew-m-leonard]

Add retry logic to sign.sh for Windows, due to frequent failures recently with 502 returned from eclipse sign service.
Also since the script uses "set -eu", if curl returns say rc 502, which is happening frequently the script exits... so added if return code check.

[andrew-m-leonard]

Successful test run with a failure: https://ci.adoptium.net/job/build-scripts/job/release/job/sign_build/26632/console

Signing ./bin/jrunscript.exe
Signing ./bin/jrunscript.exe using Eclipse Foundation codesign service
curl: (22) The requested URL returned error: 502 
curl command failed, sign of ./bin/jrunscript.exe failed
Code Not Signed For File ./bin/jrunscript.exe
1 Of 20
curl: (22) The requested URL returned error: 502 
curl command failed, ./bin/jrunscript.exe Failed Signing On Attempt 1
2 Of 20
./bin/jrunscript.exe Signed OK On Attempt 2

[steelhead31]

LGTM!