Drop orderable from hst:pages, hst:templates, hst:sitemap and hst:workspace nodetype definition

See HSTTWO-4130 for earlier discussion and context.

Conclusion thereafer was that for hst:pages and hst:templates there is (or should be) no technical or functional reason to keep orderable of these node types.

Looking at the current hst-types.cnd, I also noticed the same (dropping orderable) is applicable to hst:sitemap and hst:workspace, so I'm going to include that change as well.

First these changes will be applied and verified against master, and when OK backported to the release/5.0 branch (target: 5.0.2)