[MM-37772] Idiomatic naming (URL, URI, API) (#18128)

* s/Url/URL/g & s/Uri/URI/g

* s/Api/API/g

api4/file_test.go

@@ -60,7 +60,7 @@ func fileBytes(t *testing.T, path string) []byte {
 
 func testDoUploadFileRequest(t testing.TB, c *model.Client4, url string, blob []byte, contentType string,
 	contentLength int64) (*model.FileUploadResponse, *model.Response, error) {
-	req, err := http.NewRequest("POST", c.ApiUrl+"/files"+url, bytes.NewReader(blob))
+	req, err := http.NewRequest("POST", c.APIURL+"/files"+url, bytes.NewReader(blob))
 	require.NoError(t, err)
 
 	if contentLength != 0 {
@@ -1049,7 +1049,7 @@ func TestGetPublicFile(t *testing.T) {
 
 	info, err := th.App.Srv().Store.FileInfo().Get(fileId)
 	require.NoError(t, err)
-	link := th.App.GeneratePublicLink(client.Url, info)
+	link := th.App.GeneratePublicLink(client.URL, info)
 
 	resp, err := http.Get(link)
 	require.NoError(t, err)
@@ -1082,7 +1082,7 @@ func TestGetPublicFile(t *testing.T) {
 	require.NoError(t, th.cleanupTestFile(fileInfo))
 
 	th.cleanupTestFile(info)
-	link = th.App.GeneratePublicLink(client.Url, info)
+	link = th.App.GeneratePublicLink(client.URL, info)
 	resp, err = http.Get(link)
 	require.NoError(t, err)
 	require.Equal(t, http.StatusNotFound, resp.StatusCode, "should've failed to get file after it is deleted")