Collect all version-based warnings into a single dialog when opening old files.

[Seth Hillbrand]

Collect a list of standard changes that are applied to a new file based on the version of file the user is opening.

Examples include:
- Removing segment-based fills
- Changing zone fill board edge stand-off
- Changing zone fill stroking

Marking here for my reference

[Jeff Young (jeyjey)]

Note that this should be pretty easy to implement using wxWidget's logging facilities. See LIB_LOGGER for an example.

(Note that the last logged message is the one that's duplicated in the list and in the dialog text, so it needs to be a generic one. We add this right before flush in the LIB_LOGGER case.)

[KiCad Janitor (kicad-janitor)]

KiCad bug tracker has moved to Gitlab. This report is now available here: https://gitlab.com/kicad/code/kicad/-/issues/2461