Dynamically generate manifest.xml for outlook plugin

[jeremyw24]

The outlook plugin requires a manifest.xml file to integrate the app to exchange 365.

Presently, the manifest.xml is served from the app directly eg. https://microsoft.poc.placeos.com/outlook/manifest.xml

However, the manifest.xml has various fields that require to be updated dynamically based on the base domain of the clients deployment, for example the AppDomain for Nestle would need to be https://nestle.placeos.run/outlook/manifest.xml

Provide method as discussed for this file to be generated by the staff-api to dynamically configure the required paths and serve without auth.

Fields required:
<AppDomain>https://microsoft.poc.placeos.com/outlook/</AppDomain>

<SourceLocation DefaultValue="https://microsoft.poc.placeos.com/outlook/"/>

<bt:Url id="functionFile" DefaultValue="https://microsoft.poc.placeos.com/outlook/function-file/function-file.html"/>

<bt:Url id="Taskpane.Url" DefaultValue="https://microsoft.poc.placeos.com/outlook/"/>

<bt:Url id="BookingsButton.Url" DefaultValue="https://microsoft.poc.placeos.com/outlook/upcoming"/>