[MM-63455] Fix Link previews with brackets when making the request (#30507)

* allow opening angle bracket before links

* cut off link before an angle bracket(both open & close)

* add more test cases for ParseURLAutolink func

* add more test cases for ParseWWWAutolink func

* add more test cases for TrimTrailingCharactersFromLink func

* add more test cases for GetFirstLinkAndImages func

* add test cases for isAllowedBeforeWWWLink func

* allow closing angle bracket and opening paranthesis before links

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/post_metadata_test.go

@@ -1727,12 +1727,27 @@ func TestGetFirstLinkAndImages(t *testing.T) {
 			ExpectedFirstLink: "",
 			ExpectedImages:    []string{},
 		},
+		"http link in angle brackets": {
+			Input:             "this is a <http://example.com>",
+			ExpectedFirstLink: "http://example.com",
+			ExpectedImages:    []string{},
+		},
+		"http link with only opening angle bracket": {
+			Input:             "this is a <http://example.com",
+			ExpectedFirstLink: "http://example.com",
+			ExpectedImages:    []string{},
+		},
+		"http link with only closing angle bracket": {
+			Input:             "this is a http://example.com>",
+			ExpectedFirstLink: "http://example.com",
+			ExpectedImages:    []string{},
+		},
 	} {
 		t.Run(name, func(t *testing.T) {
 			firstLink, images := th.App.getFirstLinkAndImages(th.Context, testCase.Input)
 
-			assert.Equal(t, firstLink, testCase.ExpectedFirstLink)
-			assert.Equal(t, images, testCase.ExpectedImages)
+			assert.Equal(t, testCase.ExpectedFirstLink, firstLink)
+			assert.Equal(t, testCase.ExpectedImages, images)
 		})
 	}