Previously, values for `ID.flag` and `ID.tag` used the prefixes `LIB_` and
`LIB_TAG` respectively. This was somewhat confusing because it's not really
related to libraries in general. This patch changes the prefix to `ID_FLAG_` and
`ID_TAG_`. This makes it more obvious what they correspond to, simplifying code.
Pull Request: https://projects.blender.org/blender/blender/pulls/125811