[WIP] check for old menutree dynamic links and attempt to convert on import.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| Refs tickets  | #1412
| License       | MIT
| Doc PR        | -

todo
 - [ ] confirm this works :smile: @espaan