[JENKINS-23191] Cannot reproduce problem in HtmlUnit test, but can at least guard against other regressions.

MockFolderTest.moving pointed out a refinement to 1197e0ce: list folders, if included, before their contents.

(cherry picked from commit abf33593)

The basic fix is to use ${rootURL} plus full model object URLs rather than relying on ${jobBaseUrl}.
This is made trickier by the fact that the model object URLs are computed inside ProgressiveRendering.compute,
and therefore will not be correct when nondefault views are in the crumb trail unless the original request information is present.
So modifying ProgressiveRendering to preserve a copy of the original request for use during computation.
(This could probably be used to simplify parts of AsynchPeople as well.)
Also improving AbstractItem.getUrl to properly construct a URL including views even when the current page is not inside the item;
it should suffice for some ancestor of the current item (or a view thereof) to be in the ancestor list of this page.

Signed-off-by: NOleg Nenashev <o.v.nenashev@gmail.com>

Signed-off-by: NOleg Nenashev <o.v.nenashev@gmail.com>

[FIXED JENKINS-12753] Added PluginStrategy.getShortName to avoid actually trying to unpack a plugin before throwing RestartRequiredException.