export_preview_data() added wrongly

[Drivingralle]

The method export_preview_data() in WP_Customize_Nav_Menus is added as a filter to the hook wp_footer (​https://developer.wordpress.org/reference/hooks/wp_footer/) as a filter but it's a action hook.

Tiny bug. I'll attach a patch.

[SergeyBiryukov]

Good catch, thanks! This does not affect anything in practice, but makes sense to correct for better semantics.

Introduced in [36889] / #27355. A similar instance​ in the WP_Customize_Widgets class, added in [27419] / #27112, already uses the correct function.

[mukesh27]

The changes make sense to me. Assign commit to Sergey.

[jorbin]

In 54120:

Customize: Use Semantically correct function

Functionally, add_action and add_filter are essentially the same, but semantically they are not.

Props Drivingralle.
Fixes #56285.

[peterwilsoncc]

@mukesh27 @SergeyBiryukov added to props via make/core per review comments above.