fix: various reflection issues with Model and Entity

[paulbalandan]

Closes #17
Fixes #19
Fixes #25

This will use CI v4.5 and PHP 8.1 so this might still hold for a while.

IN PROGRESS

To do:

• Use codeigniter4/codeigniter4:4.5.x-dev branch while v4.5 is not yet released (this will be removed after v4.5 release) Require codeigniter4/framework@^4.5
• Remove hacks to downgrade release (to support PHP 8.1+ solely)
• Require phpstan/phpstan@^1.11 and friends
• Use SQLite to store database (to obtain an accurate picture of the database, we'll use a live database created from the user's migration files)
• Add representations of the database, tables, and columns (value objects)
• Add migrations helper
• Add model/entity casts helper (that is aligned with new cast behavior in 4.5)
• Add entity property extension for dynamic fetch of entity properties
• Add entity method extension
• Add model method extension
• Add phpstan rules