[Scripting] Use the LazyBindings instead of SimpleBindings

At various modules Sling Scripting (and Sling Models) code still uses a SimpleBindings implementation of the Bindings, while it could use LazyBindings which are more efficient in case not all provided bindings are required.
While the scripting itself does not necessarily use a LazyBindings.Supplier, other BindingValueProviders can be invoked on them, which do support the LazyBindings; and in that case there can be a benefit.

Requires a bump of the dependency to Sling API though (at least 2.21.0 is required)