Anim: Separate keying flags

Splits the flag `..._FLAG_INSERTNEEDED` between autokey and
manual keying. The fact that this flag was shared between the two
systems has been the cause of issues in the past. It wouldn't
let you insert a keyframe even though you explicitly used an operator
to do so.

In order to be clearer what options are used where, the user preferences
have been reordered.

By default "Only Insert Needed" will be enabled for auto-keying, but not for manual keying.
The versioning code will enable both if it was enabled previously.

# Code side changes

The keying system has flags that define the behavior
when keys are inserted. Some of those flags were shared
between keying and auto-keying. Some were only used for
auto-keying.
To clarify that, prefix flags that used exclusively in one or the other
system with `AUTOKEY`/`MANUALKEY`

Also the flag name on the user preferences and the tool settings was renamed.
Previously it was called `autokey_flag`. To indicated that it is not only used
for autokeying, rename it `keying_flag`.

Fixes: #73773

Pull Request: https://projects.blender.org/blender/blender/pulls/115525

tests/python/bl_animation_keyframing.py

@@ -256,6 +256,7 @@ class AutoKeyframingTest(AbstractKeyframingTest, unittest.TestCase):
         bpy.context.scene.tool_settings.use_keyframe_insert_auto = True
         bpy.context.preferences.edit.use_keyframe_insert_available = False
         bpy.context.preferences.edit.use_keyframe_insert_needed = False
+        bpy.context.preferences.edit.use_auto_keyframe_insert_needed = False
 
     def tearDown(self):
         super().tearDown()
@@ -291,6 +292,7 @@ class InsertAvailableTest(AbstractKeyframingTest, unittest.TestCase):
         bpy.context.scene.tool_settings.use_keyframe_insert_auto = True
         bpy.context.preferences.edit.use_keyframe_insert_available = True
         bpy.context.preferences.edit.use_keyframe_insert_needed = False
+        bpy.context.preferences.edit.use_auto_keyframe_insert_needed = False
 
     def tearDown(self):
         super().tearDown()
@@ -385,12 +387,14 @@ class InsertNeededTest(AbstractKeyframingTest, unittest.TestCase):
         super().setUp()
         bpy.context.scene.tool_settings.use_keyframe_insert_auto = True
         bpy.context.preferences.edit.use_keyframe_insert_needed = True
+        bpy.context.preferences.edit.use_auto_keyframe_insert_needed = True
         bpy.context.preferences.edit.use_keyframe_insert_available = False
 
     def tearDown(self):
         super().tearDown()
         bpy.context.scene.tool_settings.use_keyframe_insert_auto = False
         bpy.context.preferences.edit.use_keyframe_insert_needed = False
+        bpy.context.preferences.edit.use_auto_keyframe_insert_needed = False
 
     def test_insert_needed_object(self):
         keyed_object = _create_animation_object()