Remove support for win32-ia32

[felipecrs]

Support for win32-ia32 target was removed from vsce a long time ago. I wonder if it should not be removed from ovsx too.

[amvanbaren]

ovsx uses vsce to package extensions (where target is used). ovsx doesn't validate the target, just passes it to vsce, so ovsx also doesn't support win32-ia32.

[felipecrs]

Maybe it should be removed from code then?

https://github.com/eclipse/openvsx/blob/master/server/src/main/java/org/eclipse/openvsx/util/TargetPlatform.java#L18
https://github.com/eclipse/openvsx/blob/master/server/src/test/java/org/eclipse/openvsx/RegistryAPITest.java#L251
https://github.com/eclipse/openvsx/blob/master/webui/src/utils.ts#L152