Add first-class Xiaomi provider support (#863)

* feat(provider): add xiaomi as first-class provider

* feat(demos): add xiaomi mimo integration demo

* refactor(demos): remove Xiaomi MiMo integration demo and update documentation

* updating model list and adding the xiamoi models

---------

Co-authored-by: Salman Paracha <salmanparacha@MacBook-Pro-389.local>

config/plano_config_schema.yaml

@@ -188,6 +188,7 @@ properties:
             - groq
             - mistral
             - openai
+            - xiaomi
             - gemini
         routing_preferences:
           type: array
@@ -235,6 +236,7 @@ properties:
             - groq
             - mistral
             - openai
+            - xiaomi
             - gemini
         routing_preferences:
           type: array