Go: add stream / think chat (#14242)

### What problem does this PR solve?

1. Supports stream and non-stream chat
2. Supports think and non-think chat
3. List supported models from DeepSeek service. (This command can be
used to verify the API validity)

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

internal/cli/types.go

@@ -73,6 +73,7 @@ const (
 	TokenKeys
 	TokenGenerate
 	TokenAvailable
+	TokenSupported
 	TokenModel
 	TokenModels
 	TokenProvider
@@ -80,6 +81,7 @@ const (
 	TokenDefault
 	TokenChats
 	TokenChat
+	TokenStream
 	TokenFiles
 	TokenAs
 	TokenParse
@@ -106,7 +108,6 @@ const (
 	TokenIndex
 	TokenVector
 	TokenSize
-	TokenDocMeta
 	TokenName // For ALTER PROVIDER <name> NAME <new_name>
 	TokenInstance
 	TokenInstances