feat: add Google Gemini Pro support (#826)

* fest: Add Google Gemini Pro, fix #810

* fest: Add tooling to Gemini; Add OpenAI-like system prompt to Gemini

* refactor: removing unused if statement

* fest: Add dummy model message for system message in gemini model

* chore: update implementation

---------

Co-authored-by: JustSong <songquanpeng@foxmail.com>

controller/model.go

@@ -423,6 +423,15 @@ func init() {
 			Root:       "PaLM-2",
 			Parent:     nil,
 		},
+		{
+			Id:         "gemini-pro",
+			Object:     "model",
+			Created:    1677649963,
+			OwnedBy:    "google",
+			Permission: permission,
+			Root:       "gemini-pro",
+			Parent:     nil,
+		},
 		{
 			Id:         "chatglm_turbo",
 			Object:     "model",