changed entry type and the modified indicators

[i-just]

Description

Steps to reproduce:

• create an entry type et1 with a plain text field in it
• create a second entry type et2 with a matrix field (in any view mode) in it
• create a section with both entry types, make sure the et1 is the first on the list
• create a new entry in that section (don’t save)
• switch entry type to et2
• click “New entry” to add a new nested entry to the matrix field
• note that the blue modified indicator doesn’t show for the matrix field

If you were to reload the page after switching the entry type, the indicators would show as expected.

This PR fixes the issue by allowing the delta names to get registered when the entry type is changed and updating the data-delta-names on the main-form container.

Related issues

n/a