Improve bundles configuration settings

With the change to support IWebJobsConfigurationStartup (https://github.com/Azure/azure-functions-host/pull/5991), I introduced a "chicken-and-egg" problem and now bundles options do not get set up correctly before they are instantiated. This means that in core tools there's no setting for the bundles path and bundle operations will fail.

There's a workaround today by explicitly setting environment variables but we need to improve this.

Will add link to workaround code once committed.

Start by reviewing the IWebJobsConfigurationStartup change in PR 5991 and trace how bundle options are initialized in core tools. Reproduce bundle operations without the environment-variable workaround; done means the bundles path is configured before bundle operations run.

Written by the indexing model from the issue text.