Add proxy_path parameter to flet_fastapi.app() (#1882)

* hotfix to enable flet-fastapi apps configured at different locations

* Using  parameter name instead of

* Fix

* Fix newline

* Fix newline

Author: flokapi

sdk/python/packages/flet-fastapi/src/flet_fastapi/app.py

@@ -16,6 +16,7 @@
 
 def app(
     session_handler: Callable[[Page], Awaitable],
+    proxy_path: Optional[str] = None,
     assets_dir: Optional[str] = None,
     app_name: Optional[str] = None,
     app_short_name: Optional[str] = None,
@@ -79,6 +80,7 @@ async def oauth_redirect_handler(request: Request):
     fastapi_app.mount(
         path="/",
         app=FletStaticFiles(
+            proxy_path=proxy_path,
             assets_dir=assets_dir,
             app_name=app_name,
             app_short_name=app_short_name,

sdk/python/packages/flet-fastapi/src/flet_fastapi/flet_static_files.py

@@ -39,6 +39,7 @@ class FletStaticFiles(StaticFiles):
 
     def __init__(
         self,
+        proxy_path: Optional[str] = None,
         assets_dir: Optional[str] = None,
         app_name: Optional[str] = None,
         app_short_name: Optional[str] = None,
@@ -50,6 +51,7 @@ def __init__(
     ) -> None:
         self.index = "index.html"
         self.manifest_json = "manifest.json"
+        self.__proxy_path = proxy_path
         self.__assets_dir = assets_dir
         self.__app_name = app_name
         self.__app_short_name = app_short_name
@@ -83,7 +85,10 @@ def lookup_path(self, path: str) -> Tuple[str, Optional[os.stat_result]]:
         return (full_path, stat_result)
 
     async def __config(self, root_path: str):
-        self.__app_mount_path = root_path
+        if self.__proxy_path:
+            self.__app_mount_path = self.__proxy_path + root_path
+        else:
+            self.__app_mount_path = root_path
 
         # where modified index.html is stored
         temp_dir = tempfile.mkdtemp()