Better error/prompt messages when images not found due to incorrect paths

[codenamewei]

Describe the bug
Need better description on logs to describe that image paths not align with the ones imported.

Description 1
Previously, if project has been reloaded once after start classifai, reloading of the project again will not go through the data points to check if the data is there.
If data paths moved after classifai started, loading will failed with no clear messages of what is going on.

Description 2
If data paths changed and classifai started after, the data points which cant found will just not loaded without clear messages in the logs saying where were the data paths which cant be found.

Two scenarios:
Prerequisite: import images

1. Rename folder/move paths before start classifai
2. Rename folder/move paths after start classifai

Expected behavior
Project reloaded successfully with log messages saying the data points paths not found (if there is any)

Jan 25, 2021 12:38:28 pm INFO  a.c.d.annotation.AnnotationVerticle - /Users/chiawei/Desktop/sample-data/Airlines/stewardess/s01.png not found. Check if the data is in the corresponding path. 
Jan 25, 2021 12:38:28 pm INFO  a.c.d.annotation.AnnotationVerticle - /Users/chiawei/Desktop/sample-data/Airlines/stewardess/s02.jpg not found. Check if the data is in the corresponding path. 
Jan 25, 2021 12:38:28 pm INFO  a.c.d.annotation.AnnotationVerticle - /Users/chiawei/Desktop/sample-data/Airlines/stewardess/s03.jpg not found. Check if the data is in the corresponding path. 

[kengeSkyMind]

Tested both scenarios and it works as intended, screenshot of the log provided as below: