Azure Function app missing host keys if WEBSITE_RUN_FROM_PACKAGE=1

**Bicep version**
Bicep CLI version 0.3.255 (589f0375df)

**Describe the bug**
Host keys are not present on the function app if the appSetting: WEBSITE_RUN_FROM_PACKAGE=1 is set.

**To Reproduce**
- Modify the Function App example main.bicep, add the following in the appSetting section:

{
name: 'WEBSITE_RUN_FROM_PACKAGE'
value: '1'
}
- deploy and observe App keys > Host Keys are blank
- if you then modify any appSetting via the portal, Configuration > Application settings, then save, the _master and default keys will appear