[4.0] Project converter: Editor hints intended to migrate to `@export_` variants comment out nontrivial syntax

[nobuyukinyuu]

Godot version

4.0 stable

System information

Windows 10

Issue description

It appears some parsing for export migration to 4.0 is not yet implemented. When exports specify an implementation that is now separate from @export, the old syntax is commented out. Two examples include syntax for @export_flags and @export_range. These will be migrated instead to @export.

Steps to reproduce

Migrate project from 3.x to 4.0

Minimal reproduction project

n/a