Update Placement snippets and templates

[TomerFi]

Placement CRD can be found here.

Resource docs can be found here.

Snippets are saved in our snippets directory.

Templates are saved in our templates directory.

VSCode Snippet Guide.
VSCode Using Snippets.

Related issue: #21

Templates are a part of our ocmNewProject command, no vscode docs available.
We have multiple templates, each template as its own Placement manifest.

[ilan-pinto]

why reopened

[TomerFi]

We updated only the templates. Not the snippet.

[TomerFi]

@ilan-pinto we're confusing #26 (channel) and this one (placement).
The recent PR updates the placement templates, but not the snippet:
https://github.com/open-cluster-management-io/ocm-vscode-extension/blob/main/snippets/placement.json

We also need to decide if we want to allow users to use old manifests. Meaning, should we add another snippet:

{
	"placement-v1alpha1": {
            ...
	},
	"placement-v1beta1": {
            ...
	}
}

Or replace the current one:

{
	"placement": {
            ...
	}
}

As you can see with the current object key, the original intention was to keep multiple versions.

[TomerFi]

fixed in #69