feat: Improve schema grammar

[fagundes]

Goal:

• Be able to use correctly project barryvdh/laravel-ide-helper, especially command php artisan ide-helper:models with oracle

Improves:

• change compileColumns
• add compileForeignKeys
• add and change tests
• improve getColumns / compileColumns, before it was possible getColumns only on user schema, now it possible retrieve columns from others schemas

Possible break change:

• change compileColumns fields:
  • string fields (like column name, column type) to lower case;
  • nullable to boolean;
  • numeric fields (like length) to int;
  • change type value based on precision and scale;
  • change length value based on type;

[yajra]

Thank you for the PR, will review this as soon as I can.

[yajra]

Released on v11.1.0 🚀 Thanks!