BHV-15685: Panels branding was causing unnecessary full-screen-repaints...

...during every panel transition. This caused lag and blinking, as well as other performance issues.

* Branding is now set once, when necessary. (Instead of every panel transition)
* Branding now has an appropriate size imposed on it. (Instead of none whatsoever)
* Breadcrumb height is now a variable.

Enyo-DCO-1.1-Signed-off-by: Blake Stephens <blake.stephens@lge.com>
Noticed something here which didn't work properly before either - if you set the `moon.Panels` starting index to a value where the branding image should appear, `this.getPanelInfo(0, this.index).breadcrumb` is falsy and no branding image appears.