* add Enabled/Disabled extensions list view

* extract viewOrder calculation logic

and return Number.MAX_VALUE instead of Number.POSITIVE_INFINITY for
views end up with undefined order, when comparing two views like this,
we get Number.MAX_VALUE - Number.MAX_VALUE = 0, rather than NaN
caused by infinity arithmetic.

* allow Installed Extensions view to be toggled off

* refine query for enabled/disabled extensions

* simplify query for enabled/disabled extensions

* disabled extensions also include built-in ones