[AB-70] moving image generation functionality to separate image generation module

removing doge image generation from default base
split rest-api into separate modules (base and extensions)

python/components/rest-api-base/python/utils/flask_utils.py

@@ -0,0 +1,24 @@
+from io import BytesIO
+
+from flask import send_file
+
+
+def serve_pil_image(pil_img):
+    img_io = BytesIO()
+    pil_img.save(img_io, 'PNG')
+    img_io.seek(0)
+    return send_file(img_io, mimetype='image/png')
+
+
+def serve_pil_gif_image(frames, duration=25):
+    animated_gif = BytesIO()
+    frames[0].save(animated_gif, format='GIF', save_all=True, append_images=frames[1:], duration=duration, loop=0, disposal=2)
+    animated_gif.seek(0)
+    return send_file(animated_gif, mimetype='image/gif')
+
+
+class ValidationException(Exception):
+    def __init__(self, provided_value, message):
+        self.provided_value = provided_value
+        self.message = message
+        super().__init__(f'{self.message}: provided value: {provided_value}')