update property names for JSON camel casing, add inDesiredState property

[SteveL-MSFT]

PR Summary

Add .DS_Store to .gitignore so I don't have to keep explicitly avoid including it
Rename JSON property names to be camelCase
Add inDesiredState to TestResult, rename diff_properties to spell out differingProperties and make it mandatory

cc @michaeltlombardi schema impact

PR Context

Fix #108

[michaeltlombardi]

What effect, if any, does this have on resources that implement their own test operation? I think this change set only applies to how DSC returns the information about a test operation, but better to be sure.

[SteveL-MSFT]

Although not implemented yet, the expectation is that resources that implement test (with state and/or diff) match the schema that dsc itself returns

[michaeltlombardi]

And in those cases, if I follow correctly:

• For State, dsc generates the differingProperties array for the resource
• For StateAndDiff, the resource is responsible for returning the array of differing properties itself

[SteveL-MSFT]

Yes, that is the expectation

[michaeltlombardi]

How does this change interact with the _inDesiredState well-known property? In the current schema/docs, we have resources that implement test using that property as part of the instance's schema, but this implies that resources which implement test return something other than the data blob for the resource instance.

In other words, given this resource's manifest snippet:

  "test": {
    // defines the command etc
    "return": "state"
  },
  "schema": {
    "embedded": {
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "type": "object",
      "properties": {
        "foo": { "type": "string" }
      }
    }
  }

The resource should return:

{"actualState": { "foo": "bar" }, "inDesiredState": false}

instead of the prior contract (which would've had _inDesiredState in the instance schema):

{ "foo": "bar", "_inDesiredState": false}

[SteveL-MSFT]

So the change here is that resources don't emit _inDesiredState anymore unless they return state then it will look like the TestResult schema.