chore: support per-device json configs (<codename>.json)

Signed-off-by: cloudy <cloudy.nguyn@outlook.com>

example_vayu.json

@@ -0,0 +1,28 @@
+{
+  "fox": {
+    "branch": "12.1",
+    "sync_dir": "~/OrangeFox_sync",
+    "build_dir": "~/fox_12.1"
+  },
+  "device": {
+    "codename": "vayu",
+    "vendor": "xiaomi",
+    "tree_repo": "https://github.com/example/android_device_xiaomi_vayu.git",
+    "tree_branch": "fox_12.1",
+    "recovery_image": "vendor_boot"
+  },
+  "build": {
+    "target": "recoveryimage",
+    "jobs": 0,
+    "ccache": true,
+    "ccache_size": "50G",
+    "clean_before_build": false
+  },
+  "env": {
+    "ALLOW_MISSING_DEPENDENCIES": "true",
+    "FOX_USE_BASH_SHELL": "1",
+    "FOX_ASH_IS_BASH": "1",
+    "FOX_USE_NANO_EDITOR": "1",
+    "OF_MAINTAINER": "your_name"
+  }
+}