PyAPI: make internal modules explicitly "private"

Rename modules in `./scripts/modules/` to use an underscore prefix to
make it clear they aren't intended to be part of public API's. This
also means there is no implication that these modules should be stable,
allowing us to change them based on Blender's internal usage.

The following modules have been marked as private:

- `animsys_refactor`
- `bl_console_utils`
- `bl_i18n_utils`
- `bl_previews_utils`
- `bl_rna_utils`
- `bl_text_utils`
- `bl_ui_utils`
- `bpy_restrict_state`
- `console_python`
- `console_shell`
- `graphviz_export`
- `keyingsets_utils`
- `rna_info`
- `rna_manual_reference`
- `rna_xml`

Note that we could further re-arrange these modules
(under `_bpy_internal` in some cases), this change is mainly to mark
them as private, further changes can be handed on a case-by-case basis.

Ref !147773

scripts/modules/_bl_i18n_utils/bl_extract_messages.py

@@ -18,7 +18,7 @@ import glob
 from pathlib import PurePath
 
 # XXX Relative import does not work here when used from Blender...
-from bl_i18n_utils import settings as settings_i18n, utils
+from _bl_i18n_utils import settings as settings_i18n, utils
 
 import bpy
 
@@ -31,7 +31,7 @@ filter_message = ignore_reg.match
 
 def init_spell_check(settings, lang="en_US"):
     try:
-        from bl_i18n_utils import utils_spell_check
+        from _bl_i18n_utils import utils_spell_check
         return utils_spell_check.SpellChecker(settings, lang)
     except Exception as ex:
         print("Failed to import utils_spell_check ({})".format(str(ex)))
@@ -1231,7 +1231,7 @@ def dump_messages(do_messages, do_checks, settings):
     # Get strings specific to translations' menu.
     for lng in settings.LANGUAGES:
         process_msg(
-            msgs, settings.DEFAULT_CONTEXT, lng[1], "Languages’ labels from bl_i18n_utils/settings.py",
+            msgs, settings.DEFAULT_CONTEXT, lng[1], "Languages’ labels from _bl_i18n_utils/settings.py",
             reports, None, settings,
         )
 

scripts/modules/_bl_i18n_utils/utils.py

@@ -22,7 +22,7 @@ import struct
 import tempfile
 import time
 
-from bl_i18n_utils import (
+from _bl_i18n_utils import (
     settings,
     utils_rtl,
 )

scripts/modules/_bl_i18n_utils/utils_languages_menu.py

@@ -56,7 +56,7 @@ def gen_menu_file(stats, settings):
         "# ID must be unique, except for 0 value (marks categories for menu).",
         "# Line starting with a # are comments!",
         "#",
-        "# Automatically generated by bl_i18n_utils/utils_languages_menu.py script.",
+        "# Automatically generated by _bl_i18n_utils/utils_languages_menu.py script.",
         "# Highest ID currently in use: {}".format(highest_uid),
     ]
     for uid_num, label, uid, flag, lvl in langs:

scripts/modules/_console_python.py

@@ -237,7 +237,7 @@ execute.hooks = []
 
 
 def autocomplete(context):
-    from bl_console_utils.autocomplete import intellisense
+    from _bl_console_utils.autocomplete import intellisense
 
     sc = context.space_data
 

scripts/modules/addon_utils.py

@@ -332,7 +332,7 @@ def enable(module_name, *, default_set=False, persistent=False, refresh_handled=
     import os
     import sys
     import importlib
-    from bpy_restrict_state import RestrictBlend
+    from _bpy_restrict_state import RestrictBlend
 
     if handle_error is None:
         def handle_error(ex):

scripts/modules/bl_app_template_utils.py

@@ -35,7 +35,7 @@ _modules = {}
 
 
 def _enable(template_id, *, handle_error=None, ignore_not_found=False):
-    from bpy_restrict_state import RestrictBlend
+    from _bpy_restrict_state import RestrictBlend
 
     if handle_error is None:
         def handle_error(_ex):

scripts/modules/bpy/utils/__init__.py

@@ -321,7 +321,7 @@ def load_scripts(*, reload_scripts=False, refresh_scripts=False, extensions=True
         # Without this, add-on register functions accessing key-map properties can crash, see: #111702.
         _bpy.context.window_manager.keyconfigs.update(keep_properties=True)
 
-    from bpy_restrict_state import RestrictBlend
+    from _bpy_restrict_state import RestrictBlend
 
     with RestrictBlend():
         for base_path in script_paths(use_user=use_user):
@@ -367,7 +367,7 @@ def _on_exit():
 
     # Call `unregister` function on internal startup module.
     # Must only be used as part of Blender 'exit' process.
-    from bpy_restrict_state import RestrictBlend
+    from _bpy_restrict_state import RestrictBlend
     with RestrictBlend():
         for mod_name in reversed(_registered_module_names):
             if (mod := _sys.modules.get(mod_name)) is None:
@@ -1231,7 +1231,7 @@ def _blender_default_map():
     # NOTE(@ideasman42): Avoid importing this as there is no need to keep the lookup table in memory.
     # As this runs when the user accesses the "Online Manual", the overhead loading the file is acceptable.
     # In my tests it's under 1/100th of a second loading from a `pyc`.
-    ref_mod = execfile(_os.path.join(_script_base_dir, "modules", "rna_manual_reference.py"))
+    ref_mod = execfile(_os.path.join(_script_base_dir, "modules", "_rna_manual_reference.py"))
     return (ref_mod.url_manual_prefix, ref_mod.url_manual_mapping)