For standalone projects, pulling in all of Illuminate\Support is a bit
overkill, given that we're using only a couple of functions from the
package. This commit opts to duplicate the two helper functions inside
the container namespace (so they'll be picked up by a subtree split),
which also removes reliance on any custom global functions.

This goes beyond effectively reverting #29959, as the container used
Arr::wrap() before adding in the value() helper.