[WIP][toolset] Add kiali support

[aljesusg]

Adding kiali toolset to kubernetes-mcp

• Adds Kiali toolset with a mesh status tool.
• Requires kiali-url when Kiali is enabled (via flag or config).
• Safer URL building and proper token forwarding to Kiali.(We use the same token to validate permissions and access, so in the local environment we also check the kubeconfig to ensure that the provided context includes valid authentication.)
• Adds focused tests for Kiali manager, client, and mesh.
• Updates help text to list Kiali as an available toolset.

We'll add others later after this first PR

cc @hhovsepy