func azure functionapp publish should support publishing dependencies (for PowerShell function apps)

Currently, PowerShell function app dependencies can be specified via `requirements.psd1`. These dependencies are downloaded and installed on the first function load (either locally or in Azure).

Once the function app is published to Azure, we download the dependencies (again) on the first function load. This contributes to cold start of about ~40 seconds just to install the Az module.

Proposal: When the function app is published, include the dependencies with it. This way, in the first function load, we skip installing the dependencies. This will help address cold start for PowerShell function apps with dedicated storage.

Please note that subsequent dependencies installation updates will be done in the background.

Start with the `func azure functionapp publish` command and its handling of `requirements.psd1`; trace how dependencies are currently obtained during the first function load. Done means published PowerShell apps include those dependencies so the first load skips installation, while later dependency updates still occur in the background.

Written by the indexing model from the issue text.