feat(i18n): introduce custom Fluent resource loader

consuming prebuilt content for easier packaging of ruyi

ruyi/i18n/fluent_adapter.py

@@ -0,0 +1,27 @@
+from typing import Generator
+
+from fluent.runtime import AbstractResourceLoader
+from fluent.syntax import FluentParser
+from fluent.syntax.ast import Resource
+
+
+class PrebuiltFluentResourceLoader(AbstractResourceLoader):
+    def __init__(self, data: dict[str, str]) -> None:
+        self._data = data
+
+    @classmethod
+    def _resource_key(cls, resource_id: str, locale: str) -> str:
+        return f"{resource_id}@{locale}"
+
+    def resources(
+        self,
+        locale: str,
+        resource_ids: list[str],
+    ) -> Generator[list[Resource], None, None]:
+        resources: list[Resource] = []
+        for resource_id in resource_ids:
+            # combine resource_id and locale
+            if content := self._data.get(self._resource_key(resource_id, locale)):
+                resources.append(FluentParser().parse(content))
+        if resources:
+            yield resources