Updated API Code Samples (#24141)

* api: remove PHP code samples

* api: remove Curl code samples

* api: remove Go code samples

* link out to marketplace exclusively for community-built drivers

* absolute path to V4_SRC

* programmatically extract x-codeSamples

* initial batch of examples

* Update api/server/main.go

Co-authored-by: Alejandro García Montoro <alejandro.garciamontoro@gmail.com>

* Update api/server/main.go

Co-authored-by: Alejandro García Montoro <alejandro.garciamontoro@gmail.com>

* Update api/server/main.go

Co-authored-by: Alejandro García Montoro <alejandro.garciamontoro@gmail.com>

* updated examples

---------

Co-authored-by: Alejandro García Montoro <alejandro.garciamontoro@gmail.com>

api/v4/source/posts.yaml

@@ -127,21 +127,6 @@
           $ref: "#/components/responses/Unauthorized"
         "403":
           $ref: "#/components/responses/Forbidden"
-      x-code-samples:
-        - lang: Go
-          source: |
-            client := model.NewAPIv4Client("https://your-mattermost-url.com")
-            client.Login("email@domain.com", "Password1")
-
-            ephemeralPost := &model.PostEphemeral{
-              UserID: "<ID OF THE USER THAT WOULD RECEIVE THE POST>",
-              Post: &model.Post{
-                ChannelId: "<ID OF CHANNEL>",
-                Message:   "<YOUR MESSAGE>",
-              },
-            }
-
-            createdPost, response := client.CreatePostEphemeral(ephemeralPost)
   "/api/v4/posts/{post_id}":
     get:
       tags: