All the arrays in the new Action DNA are named singularly (`layer_array`,
`fcurve_array` etc). `channelbags_array` was the only plural one. For
consistency, this is now also singular.
Note that this is a backward-incompatible change, and will effectively
erase all animation from layered Actions. No effort is taken to handle this
rename as the feature is still in its experimental phase.
Action and slot assignments are not affected by this change.
Apart from the lack of backward compatibility, no functional changes are
expected.
Pull Request: https://projects.blender.org/blender/blender/pulls/124768
cf2dcc792c