Lets GetChocolatey should have a way to refresh the configuration file when it changes.

## Is Your Feature Request Related To A Problem? Please describe.

In Chocolatey GUI we use chocolatey.lib to instantiate a `Lets.GetChocolatey` object. This object then is long lived while Chocolatey GUI is running. This means any changes to the configuration made while Chocolatey GUI is running do not reflect in Chocolatey itself.

## Describe The Solution. Why is it needed?

It would be good to have a way to either tell the object to refresh it's configuration information, or for it to do it itself and possibly report back to the process that's holding the object.

## Additional Context.

Chocolatey Agent also has similar needs.

## Related Issues

- https://github.com/chocolatey/ChocolateyGUI/pull/955
- https://github.com/chocolatey/ChocolateyGUI/issues/494

Start with the long-lived Lets.GetChocolatey object described in the issue and trace how its configuration is loaded and consumed by Chocolatey GUI and Chocolatey Agent. Decide the refresh or notification behavior and document what callers can observe when configuration changes; the work is done when those processes can use updated configuration without recreating the object.

Written by the indexing model from the issue text.