New-DudDashboard - avoid loading file structure into cache every time.

[itfranck]

CUrrently, in the New-DUDDashboard cmdlet, the files are loaded into memory and most of the magic happens there.

Triggering an update will call that again and reload everything.
It was by design except after consideration, it shouldn't be done everytime and rather "on-demand" to avoid performance impact for a production dashboard where dashboard update trigger comes from anything else than a file change (which should 99% of the time outside of development).