Allow severity and default handling for missing Secrets

SUMMARY

The current behavior for the Mobile.BuildTools when a property does not exist is to simply not generate the property and generate a build error. Since v2 now defines which properties should exist we have a bit more context to evaluate. We should optionally allow either build time warnings with a default value for the missing property or allow you define a default value.

DETAILS

There are many times a "Secret" isn't really a secret as much as it is a configuration value that may be safe to check into source control. Some of these values such as an App Center Secret only ever matter for an official build and are not really utilized for Dev builds. We will want to introduce a new enum in the configuration. This should be set on both a project level and property level.

Value	Behavior
Default	We will continue to throw errors unless a default value has been provided or another value was set explicitly on the property
Error	This would be the default anyway for the project level. However you may wish to warn at the project level and only generate errors for specific properties. Any default value added will be ignored if this was set at the Property level.
Warn	We will log a build warning about the missing property but will use either the type default value or a specified default value
UseDefaultValue	Just like with warn we with use the type default value or specified default value, but no logging will occur to tell you that this occurred.

{
  "$schema": "https://mobilebuildtools.com/schemas/v2/buildtools.schema.json",
  "projectSecrets": {
    "AwesomeApp": {
      "ifMissing": "Default",
      "properties": [
        {
          "name": "AppCenterSecret",
          "type": "String",
          "isArray": false,
          "ifMissing": "UseDefaultValue"
        },
        {
          "name": "BackendApi",
          "type": "Uri",
          "isArray": false,
          "ifMissing": "Warning",
          "defaultValue": "https://dev.api.contoso.com/"
        },
        {
          "name": "SyslogPort",
          "type": "int",
          "isArray": false,
          "ifMissing": "Default",
          "defaultValue": "514"
        },
        {
          "name": "ClientId",
          "type": "Guid",
          "isArray": false,
          "ifMissing": "Default"
        }
      ]
    }
  }

Looking at this sample configuration we would make the following assertions on the properties

Property	Assertion
AppCenterSecret	This will silently be set to `default`
BackendApi	This will log a warning that no value was provided, but will set the value to `https://dev.api.contoso.com/`
SyslogPort	This will log a warning that no value was provided, but will set the value to 514
ClientId	This will log an error failing the build if no value was set in the secrets.json

dansiegel / Mobile.BuildTools

Allow severity and default handling for missing Secrets #120

SUMMARY

DETAILS