* refactor: make ShutdownManager Clone
ShutdownManager can be clone since its underlying types from tokio are
all shareable via clone.
* refactor: make ShutdownToken not Clone
Alters the API so that the ShutdownToken is not cloneable. This will help
ensure that the Drop implementation is invoked from the correct place.
This ensures a ShutdownToken will invoke `complete` by calling it from
its `Drop` implementation. This means registered components are not
required to signal completion, but can if needed.
Some comments and other cleanup refactoring was done as well.
* feat: add influxdb3_shutdown crate
provides basic wait methods for unix/windows OS's
* feat: graceful shutdown
* docs: add rust docs and test to influxdb3_shutdown
Added rustdoc comments to types and methods in the influxdb3_shutdown
crate as well as a test that shows the ordering of a shutdown.
Trevor Hilton