implement sentry transport to write crash reports to XDG_STATE_HOME

pkg/sentry/envelope.zig

@@ -7,4 +7,12 @@ pub const Envelope = opaque {
     pub fn deinit(self: *Envelope) void {
         c.sentry_envelope_free(@ptrCast(self));
     }
+
+    pub fn writeToFile(self: *Envelope, path: []const u8) !void {
+        if (c.sentry_envelope_write_to_file_n(
+            @ptrCast(self),
+            path.ptr,
+            path.len,
+        ) != 0) return error.WriteFailed;
+    }
 };