Fix CakePHP 5.3 compatibility in ModelPropertyFactory

[jamisonbryant]

Summary

Fixes CakePHP 5.3 compatibility issue where ModelPropertyFactory breaks because __debugInfo() now returns Column objects instead of arrays.

Changes

• Replace __debugInfo() with getColumn() for column default value
• Simplify isPrimaryKey() to use getPrimaryKey() public API

Both methods are stable public API that return arrays for backwards compatibility.

Fixes mixerapi/mixerapi-dev#159

[cnizzardini]

@jamisonbryant holding off on tagging this into a release because it just occured to me to ask if this change is backwards compatible with 5.0 - 5.2?

[segy]

@cnizzardini i think changing the cakephp dependency to ^5.3 in composer.json for the new version would be fine

[cnizzardini]

Yes, if I must, but I prefer to do a revision and not a minor. I still have not had time to set down and test BC on this. I also don't really want to support < 5.3 and >= 5.3 when I can just support ^5.0. Who would want that extra work?

[cnizzardini]

https://github.com/mixerapi/core/releases/tag/v2.1.1

[jamisonbryant]

Here's a little more context for this PR:

1. As part of the ongoing cakephp/migrations overhaul, the Cake core is leaning more heavily on objects instead of arrays for storing column metadata. Several of these objects were imported into cakephp/cakephp, see: Add Column from migrations cakephp/cakephp#18748.
2. One of the changes in the above PR was changing the type of the $_constraints and $_columns properties in TableSchema.php from "mostly arrays" to "arrays of objects".
   1. Before: https://github.com/cakephp/cakephp/blob/5.0.0/src/Datasource/SchemaInterface.php#L67
   2. After: https://github.com/cakephp/cakephp/blob/5.3.0/src/Datasource/SchemaInterface.php#L67
3. mixerapi/core relies on the __debugInfo() function to introspect some column metadata for identifying primary keys. Since __debugInfo() just returns $this->_columns directly, it now returns Column objects instead of arrays.

This would have resulted in an error like "Fatal error: Cannot use object of type Cake\Database\Schema\Column as array in vendor/mixerapi/core/src/Model/ModelPropertyFactory.php on line 38".

Summary: MixerAPI Core was using an internal method (though not labeled as such, which can potentially be corrected) and when some property types changed upstream, a change was necessary to switch to the stable public API.