[revert][scenic] Cleanup dev tools; allow short pkg-names

This reverts commit 94b40578.

Reason for revert:

This breaks developers and SDK customers working on components with
schemes other than fuchsia-pkg://

Original change's description:
> [scenic] Cleanup dev tools; allow short pkg-names
>
> Convert these tools usage information to be more in-line with other
> developer tools.
>
> Test: Ran tiles, present_view, set_root_view;
>   used arguments:
>   --h
>   noodles
>   fuchsia-pkg://fuchsia.com/noodles#meta/noodles.cmx
>
> Change-Id: I44a0ee8d528078283f59aa42c1f7ac74aa5ee5b2

TBR=jjosh@google.com,mikejurka@google.com,jaeheon@google.com,dworsham@google.com,adamgousetis@google.com

Not skipping CQ checks because original CL landed > 1 day ago.

Change-Id: I0dafb137581dd595b009f2f318cea2092021d56d