[java-source-utils] Add $schema to CGManifest.json (#1035)

Context: https://www.jsonschemavalidator.net/
Context: https://github.com/JamieMagee/verify-cgmanifest
Context: https://json.schemastore.org/component-detection-manifest.json
Context: dotnet/android-libraries#608

There is a [JSON Schema][0] for `CGManifest.json`.

Update `tools/java-source-utils/CGManifest.json` so that it conforms
to the JSON schema.  This involves three sets of changes:

  * Add a `$schema` property.

  * Add a `version` property; I can't find any actual documentation
    for this schema, but the [sample manifest][1] uses `"version": 1`,
    so use the same version.

  * "camelCase" all the JSON property names.  From the
    [JamieMagee/verify-cgmanifest README.md][2]:

    > Component Detection will accept object properties in PascalCase,
    > but JSON schema does not have a case-insensitive mode.
    > Camel case is the most common way to write object properties in
    > JSON.

With these changes, `CGManifest.json` reports no errors when using
<https://www.jsonschemavalidator.net>.

Co-authored-by: Jamie Magee <jamie.magee@microsoft.com>

[0]: https://json.schemastore.org/component-detection-manifest.json
[1]: https://github.com/JamieMagee/verify-cgmanifest/blob/2adfb450cd1f2170c3df120036f4a531285167ef/cgmanifest.sample.json
[2]: https://github.com/JamieMagee/verify-cgmanifest/blob/2adfb450cd1f2170c3df120036f4a531285167ef/README.md

tools/java-source-utils/CGManifest.json

@@ -1,26 +1,28 @@
 {
-    "Registrations": [
+    "$schema": "https://json.schemastore.org/component-detection-manifest.json",
+    "version": 1,
+    "registrations": [
         {
-            "Component": {
-                "Type": "maven",
-                "Maven": {
-                    "GroupId": "com.github.javaparser",
-                    "ArtifactId": "javaparser-core",
-                    "Version": "3.16.1"
+            "component": {
+                "type": "maven",
+                "maven": {
+                    "groupId": "com.github.javaparser",
+                    "artifactId": "javaparser-core",
+                    "version": "3.16.1"
                 }
             },
-            "DevelopmentDependency":false
+            "developmentDependency":false
         },
         {
-            "Component": {
-                "Type": "maven",
-                "Maven": {
-                    "GroupId": "com.github.javaparser",
-                    "ArtifactId": "javaparser-symbol-solver-core",
-                    "Version": "3.16.1"
+            "component": {
+                "type": "maven",
+                "maven": {
+                    "groupId": "com.github.javaparser",
+                    "artifactId": "javaparser-symbol-solver-core",
+                    "version": "3.16.1"
                 }
             },
-            "DevelopmentDependency":false
+            "developmentDependency":false
         }
     ]
-}
+}