Feature/search after before on (#9219)

* initial implementation of after, before, on search flags allowing to restrict the search to a specific day or a date range

* missed setting beforeDate in SearchParams in one place

* fixed condition when only flags are used for search without any plain terms

* changed date format used for after/before/on flags to be in ISO8601 format as suggested in PR comments, added a helper function to pad month and day with zeroes allowing the user user either format, with or without leading zeroes

* corrected expected compare to date setting for the TestParseDateFilterToTimeISO8601 test

* fixed a bug for the scenario when you only have the date flags without any terms, added a couple of tests for that scenario

* updated the date filter logic to use parameters to construct the query instead of simply appending strings together, as suggested in the pull request comments

* added search unit test using date flags

* added a helper function to create a test post with a createat date manually set, updated the test for search using date flags to create test posts with different createat dates to be able to better test the functionality

* MM-11817 Add support for after/before/on search flags with Elasticsearch

* add support to search posts to perform the search in context of the client's timezone when filtering by createat date using on: after: before: flags

* updated tests to match the new signature

model/client4.go

@@ -2140,8 +2140,16 @@ func (c *Client4) GetPostsBefore(channelId, postId string, page, perPage int, et
 
 // SearchPosts returns any posts with matching terms string.
 func (c *Client4) SearchPosts(teamId string, terms string, isOrSearch bool) (*PostList, *Response) {
-	requestBody := map[string]interface{}{"terms": terms, "is_or_search": isOrSearch}
-	if r, err := c.DoApiPost(c.GetTeamRoute(teamId)+"/posts/search", StringInterfaceToJson(requestBody)); err != nil {
+	params := SearchParameter{
+		Terms:      &terms,
+		IsOrSearch: &isOrSearch,
+	}
+	return c.SearchPostsWithParams(teamId, &params)
+}
+
+// SearchPosts returns any posts with matching terms string.
+func (c *Client4) SearchPostsWithParams(teamId string, params *SearchParameter) (*PostList, *Response) {
+	if r, err := c.DoApiPost(c.GetTeamRoute(teamId)+"/posts/search", params.SearchParameterToJson()); err != nil {
 		return nil, BuildErrorResponse(r, err)
 	} else {
 		defer closeBody(r)