class WakeLeaseProvider

This class is **not** threadsafe! `WakeLeaseProvider` and

`WakeLease` pointers returned from `StartOperation` must be used

on the same thread!

Provides shared pointers to `WakeLeases` which are effectively

fdf_power::WakeLease objects. This provides RAII semantics to manage the

lifecycle of the underlying wake lease such that for a given

`WakeLeaseProvider` there is _at_ _most_ one WakeLease in

existence at any moment. It is worth noting that WakeLease only acquires a

wake lease from the system if the system starts to suspend while the

WakeLease is held.

Using `WakeLeaseProvider` can have performance advantages over

using a WakeLease directly because the provider monitors system state

over its lifetime, allowing it to avoid certain operations vs a series of

shorter-lived `WakeLease` instances which would each only observe system

state while they exist.

The main difference between the shared pointer to a `WakeLease`

from `WakeLeaseProvider` and an `ManualWakeLease` is that with

`WakeLease` we get long-lived system state monitoring and

ergonomic RAII management of the actual lease. With `ManualWakeLease` you

can get long-lived system state monitoring with `End` calls and sacrifice

RAII ergonomics **or** get RAII ergonomics, but lose system state knowledge

after the `ManualWakeLease` is destroyed.