[Form] *_SET_DATA events are now guaranteed to be fired *after* the initial children were added
merged branch bschussek/issue7873 (PR #7878)

This PR was merged into the master branch.

Discussion
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[Form] *_SET_DATA events are now guaranteed to be fired *after* the initial children were added

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | yes
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #7873
| License       | MIT
| Doc PR        | -

Commits
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441222e [Form] *_SET_DATA events are now guaranteed to be fired *after* the initial children were added