feat: add getResource tool to retrieve live resource manifest

[alexmt]

Closes #63

PR adds getResource tool that allows retrieving live resource manifest .

[alexmt]

@leoluz earlier we've agreed to add getResources with filtering but I realized that Argo CD does not really have getResources (in our conversation I was thinking about different API ). So I think getResource is the best we can do.

[leoluz]

@alexmt That is a great starting point. Thank you Alex!
However, unfortunately, it leaves us in an non desired stage because we need to send one request to get the list of all resources first with /api/v1/applications/<app>/resource-tree. Such method isn't available in the current MCP today and even if it was, we would have to send multiple requests to the MCP to get the state of every resource which is not ideal. As the next step I can create a proposal in Argo CD to expose a new API to get the live state of every resource in the app and then we could use that API in the MCP.

[alexmt]

@alexmt , the getResourceTree is actually available. It is possible to ask AI to give manifests of all resources - it should call getResourceTree and then getResource on by one. It indeed will be a lot of resource requests.