schema: write_files defaults, versions $ref full URL and add vscode (#1479)

schema: write_files defaults, versions $ref full URL and add vscode

* Set write_files.permissions and content defaults the correct "string"
   data type. This aids in vscode auto-completion which injects default
   values for defined cloud-config keys.

* Make the $ref URI a full URL to our schema-cloud-config-v1.json
   JSON schema Draft-04 does not support relative $ref URLs which
   prevents validators like https://www.jsonschemavalidator.net/
   from parsing our versions schema with the error:
      Error when resolving schema reference './schema-cloud...json'.

* Add vscode exstentions for validatating #cloud-config YAML
    Developers using the cloud-init repo are likely to also
    want to create #cloud-config YAML files for development. Provide
    the suggested YAML extension in .vscode/extensions.json.

    This YAML extension will prompt vscode developers with the
    following message upon opening the cloud-init repo:

      'YAML' extension is recommended for this repository. Do you want
      to install?

    This RedHat YAML extension sources public schemas from
    https://schemastore.org and will treat the following file formats
    as #cloud-config files:

      cloud-init.yaml
      cloudinit.yaml
      *.cloud-init.yaml
      *.cloudinit.yaml

    Any filenames matching those formats will get automatic validation
    against cloud-config schema and auto-complete known #cloud-config
    keys.

1 files changed, 5 insertions, 0 deletions

diff --git a/.vscode/extensions.json b/.vscode/extensions.json
new file mode 100644
index 00000000..6098b6eb
--- /dev/null
+++ b/.vscode/extensions.json
@@ -0,0 +1,5 @@
+{
+  "recommendations": [
+    "redhat.vscode-yaml"
+  ]
+}