my.fbmessenger: move fbmessenger.py into fbmessenger/export.py

keeping it backwards compatible + conditional warning similar to https://github.com/karlicoss/HPI/pull/179

follow up for https://github.com/seanbreckenridge/HPI/pull/18
for now without the __path__ hacking, will do it in bulk later

too lazy to run test_import_warnings.sh on CI for now, but figured I'd commit it for the reference anyway

tests/test_import_warnings.sh

@@ -0,0 +1,62 @@
+#!/bin/bash
+set -eu
+
+errors=0
+function expect_warn () {
+    echo "check: " "$@"
+    [[ $(2>&1 "$@" | grep -c DEPRECATED) -gt 0 ]] || {
+        echo "ERROR: " "$@"
+        errors=1
+    }
+}
+
+function expect_ok () {
+    echo "check: " "$@"
+    [[ $(2>&1 "$@" | grep -c DEPRECATED) -eq 0 ]] || {
+        echo "ERROR: " "$@"
+        errors=1
+    }
+}
+
+
+# TODO actually this one might be ok? nothing wrong with it in principle
+expect_warn python3 -c 'from   my import fbmessenger'
+echo                   'from   my import fbmessenger' > /tmp/script.py
+expect_warn python3 /tmp/script.py
+
+expect_warn python3 -c 'from   my.fbmessenger import messages'
+echo                   'from   my.fbmessenger import messages' > /tmp/script.py
+expect_warn python3 /tmp/script.py
+
+expect_warn python3 -c 'from   my.fbmessenger import *'
+echo                   'from   my.fbmessenger import *' > /tmp/script.py
+expect_warn python3 /tmp/script.py
+
+expect_warn python3 -c 'import my.fbmessenger'
+echo                   'import my.fbmessenger' > /tmp/script.py
+expect_warn python3 /tmp/script.py
+
+expect_warn python3 -m my.core query  my.fbmessenger.messages
+expect_warn python3 -m my.core doctor my.fbmessenger
+
+
+expect_ok   python3 -c 'from   my.fbmessenger.export import *'
+echo                   'from   my.fbmessenger.export import *' > /tmp/script.py
+expect_ok   python3 /tmp/script.py
+
+
+# TODO kinda annoying: this doesn't work, and doesn't seem like traceback has anything
+# guess it's fine, kind of a border case
+# expect_ok   python3 -c 'from   my.fbmessenger import export'
+echo                   'from   my.fbmessenger import export' > /tmp/script.py
+expect_ok   python3 /tmp/script.py
+
+expect_ok   python3 -c 'import my.fbmessenger.export'
+echo                   'import my.fbmessenger.export' > /tmp/script.py
+expect_ok   python3 /tmp/script.py
+
+expect_ok   python3 -m my.core query  my.fbmessenger.export.messages
+expect_ok   python3 -m my.core doctor my.fbmessenger.export
+
+
+exit $errors