Update cgmanifest to align with the JSON schema

[jeffhandley]

With dotnet/machinelearning#7283, we realized that the cgmanifest.json file was not aligned with the JSON schema. It is using Title case property names but it should be using camelCase property names. See this comment for more detail: dotnet/machinelearning#7283 (comment)

I'm following up by updating each CG manifest in the dotnet org where we had the same issue, and this match was found at https://github.com/dotnet/dotnet/blob/main/src/source-build-externals/src/azure-activedirectory-identitymodel-extensions-for-dotnet/build/cgmanifest.json.

Here's the console app I used to confirm the existing manifest isn't valid against its schema, and the updated one in this PR is valid:

using System;
using System.Net.Http;
using System.Text.Json.Nodes;
using System.Threading.Tasks;
using Json.Schema; // Requires package JsonSchema.Net

HttpClient httpClient = new();

string schemaUrl = "https://json.schemastore.org/component-detection-manifest.json";
HttpResponseMessage schemaResponse = await httpClient.GetAsync(schemaUrl);
schemaResponse.EnsureSuccessStatusCode();
string schemaJson = (await schemaResponse.Content.ReadAsStringAsync()).Replace("/draft-04/", "/draft-06/");
JsonSchema schema = JsonSchema.FromText(schemaJson);

string[] manifestUrls = [
    "https://raw.githubusercontent.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/refs/heads/dev/build/cgmanifest.json",
    "https://raw.githubusercontent.com/jeffhandley/azure-activedirectory-identitymodel-extensions-for-dotnet/refs/heads/jeffhandley/cgmanifest/build/cgmanifest.json"
];

foreach (var manifestUrl in manifestUrls)
{
    HttpResponseMessage manifestResponse = await httpClient.GetAsync(manifestUrl);
    manifestResponse.EnsureSuccessStatusCode();
    string manifestJson = await manifestResponse.Content.ReadAsStringAsync();

    JsonNode manifest = JsonNode.Parse(manifestJson);

    var result = schema.Evaluate(manifest);
    Console.WriteLine(manifestUrl);
    Console.WriteLine($"Valid: {result.IsValid}");
    Console.WriteLine();
}

Here's the output:

https://raw.githubusercontent.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/refs/heads/dev/build/cgmanifest.json
Valid: False

https://raw.githubusercontent.com/jeffhandley/azure-activedirectory-identitymodel-extensions-for-dotnet/refs/heads/jeffhandley/cgmanifest/build/cgmanifest.json
Valid: True

[jeffhandley]

FYI after merging dotnet/runtime#109453 with the same change, I dug in to understand why/how the component governance integration was still working despite the JSON document not adhering to the schema. I was able to confirm that it was working before, and it's still working after this change. The reason it worked is that the component detection that processes these files has the JSON deserialization set up where it is recognizing either TitleCase or properCase property names.

So while it was working before, we're now adhering to the schema correctly and we won't get tripped up if the component detection ever applies stricter validation of the documents.