Restored ToJSON encoding (sans Integration) for Post APIs (#19279)

* Restored ToJSON encoding sans Integration for Post APIs

* PR feedback + GetPost test

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

model/post.go

@@ -6,6 +6,7 @@ package model
 import (
 	"encoding/json"
 	"errors"
+	"io"
 	"net/http"
 	"regexp"
 	"sort"
@@ -227,6 +228,11 @@ func (o *Post) ToJSON() (string, error) {
 	return string(b), err
 }
 
+func (o *Post) EncodeJSON(w io.Writer) error {
+	o.StripActionIntegrations()
+	return json.NewEncoder(w).Encode(o)
+}
+
 type GetPostsSinceOptions struct {
 	UserId                   string
 	ChannelId                string