Move to Symfony Flex

The structure changed completely.
Bundles are gone. Everything is flatten in the folder `src`.
I separated import & api controllers to avoid _pollution_ in the main controller folder.

config/packages/dev/framework.yaml

@@ -0,0 +1,9 @@
+framework:
+    router:
+        strict_requirements: true
+    profiler:
+        only_exceptions: false
+
+    mailer:
+        # see https://mailcatcher.me/
+        dsn: smtp://127.0.0.1:1025

config/packages/dev/jsm_serializer.yaml

@@ -0,0 +1,7 @@
+jms_serializer:
+    visitors:
+        json_serialization:
+            options:
+                - JSON_PRETTY_PRINT
+                - JSON_UNESCAPED_SLASHES
+                - JSON_PRESERVE_ZERO_FRACTION

config/packages/dev/monolog.yaml

@@ -0,0 +1,19 @@
+monolog:
+    handlers:
+        main:
+            type: stream
+            path: "%kernel.logs_dir%/%kernel.environment%.log"
+            level: debug
+            channels: ["!event"]
+        # uncomment to get logging in your browser
+        # you may have to allow bigger header sizes in your Web server configuration
+        #firephp:
+        #    type: firephp
+        #    level: info
+        #chromephp:
+        #    type: chromephp
+        #    level: info
+        console:
+            type: console
+            process_psr_3_messages: false
+            channels: ["!event", "!doctrine", "!console"]

config/packages/dev/web_profiler.yaml

@@ -0,0 +1,3 @@
+web_profiler:
+    toolbar: true
+    intercept_redirects: false