fix: filtering by post type wasn't working [BD-38] [TNL-9609] (#82)

Fixes an issue where filtering by post type wasn't working, since the filter wasn't being passed to the API.
It also simplifies the code a bit and adds tests.

src/data/constants.js

@@ -8,6 +8,7 @@ export const API_BASE_URL = getConfig().LMS_BASE_URL;
  * @enum {string}
  */
 export const ThreadType = {
+  ALL: 'all',
   QUESTION: 'question',
   DISCUSSION: 'discussion',
 };
@@ -88,17 +89,6 @@ export const ThreadViewStatus = {
   UNANSWERED: 'unanswered',
 };
 
-/**
- * Enum for filtering user posts.
- * @readonly
- * @enum {string}
- */
-export const MyPostsFilter = {
-  MY_POSTS: 'myPosts',
-  MY_DISCUSSIONS: 'myDiscussions',
-  MY_QUESTIONS: 'myQuestions',
-};
-
 /**
  * Enum for filtering posts by status.
  * @readonly
@@ -112,17 +102,6 @@ export const PostsStatusFilter = {
   UNANSWERED: 'statusUnanswered',
 };
 
-/**
- * Enum for filtering all posts.
- * @readonly
- * @enum {string}
- */
-export const AllPostsFilter = {
-  ALL_POSTS: 'allPosts',
-  ALL_DISCUSSIONS: 'allDiscussions',
-  ALL_QUESTIONS: 'allQuestions',
-};
-
 /**
  * Enum for filtering topics.
  * @readonly