Refactor: Remove `BKE_XXX_localize()`, in favor of using regular ID copying code.

Besides the NodeTree case (which remains unchanged), the localize code
is only used in one place (to generate previews of shading data-blocks).

This commit introduces a new `LIB_ID_CREATE_LOCAL` option for ID
creation/copying, which essentially implements the behavior of the
removed `BKE_XXX_localize()` functions into regular mainstream ID copy
code. When this option is set:
- new ID is tagged with `LIB_TAG_LOCALIZED`;
- Some ID copying callbacks have specific behaviors, mainly the root
  nodetree of shading IDs gets duplicated with specialized
  `ntreeLocalize()` function.

Note that I would not consider getting rid of `ntreeLocalize` for now,
this function is recursive, which should ideally never happen within ID
management copying code (this introduces all kind of complications).

No behavioral change expected from this commit.

1 files changed, 6 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_lib_id.h b/source/blender/blenkernel/BKE_lib_id.h
index c3c4c228b61..33ccd20bcff 100644
--- a/source/blender/blenkernel/BKE_lib_id.h
+++ b/source/blender/blenkernel/BKE_lib_id.h
@@ -99,6 +99,12 @@ enum {
   /** Do not tag new ID for update in depsgraph. */
   LIB_ID_CREATE_NO_DEG_TAG = 1 << 8,
 
+  /** Very similar to #LIB_ID_CREATE_NO_MAIN, and should never be used with it (typically combined
+   * with #LIB_ID_CREATE_LOCALIZE or #LIB_ID_COPY_LOCALIZE in fact).
+   * It ensures that IDs created with it will get the #LIB_TAG_LOCALIZED tag, and uses some
+   * specific code in some copy cases (mostly for node trees). */
+  LIB_ID_CREATE_LOCAL = 1 << 9,
+
   /* *** Specific options to some ID types or usages. *** */
   /* *** May be ignored by unrelated ID copying functions. *** */
   /** Object only, needed by make_local code. */