add AbstractTextFile to ingest_envoy

apps/cli/executables/pexable/ingest_envoy/ingest_envoy/schema.py

+from __future__ import annotations
+
+from pathlib import Path
+
+"""
+Adapted from shared/system to avoid including ssa-workspaces in pex
+"""
+
+
+class JSONSerializable:
+    def __json__(self, request=None) -> dict:
+        """
+        Allows this object to be converted to JSON
+
+        :param request: this parameter is the active Pyramid request, if applicable (None otherwise)
+        :return: a dictionary which can be converted to JSON using json.dump
+        """
+        pass
+
+    @classmethod
+    def from_json(cls, json: dict) -> any:
+        pass
+
+
+class AbstractTextFile(JSONSerializable):
+    """
+    Abstract text file is exactly that, an abstract concept of what a file is, to be
+    returned from various non-filesystem places.
+    """
+
+    def __init__(self, filename: str, content: str):
+        self.filename, self.content = filename, content
+
+    def write_to(self, directory: Path):
+        (directory / self.filename).write_text(self.content)
+
+    @classmethod
+    def from_path(cls, path: Path) -> AbstractTextFile:
+        return cls(path.name, path.read_text())