[11.x] Add support for modifying generated columns

[hafezdivandari]

Related to #48864 and #48357, this PR adds support for inspecting generated columns and fixes modifying them on SQLite and renaming them on legacy MySQL / MariaDB database.

Enhancements

• Modifying generated columns on SQLite
• Renaming generated columns on Legacy MySQL (< 8.0.3) and MariaDB (<10.5.2)
• Add generation to Schema::getColumns()
  • generation (null|array):
    • type (string): Generation type: 'stored' or 'virtual'.
    • expression (string): Generation expression.

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[ccharz]

This merge request causes issues with Postgres < 12. The column "attgenerated" used in src/Illuminate/Database/Schema/Grammars/PostgresGrammar.php was only added in PostgreSQL 12 according to https://pgpedia.info/p/pg_attribute.html

[driesvints]

@hafezdivandari ^

[hafezdivandari]

@driesvints Pgsql 12+ support on Laravel 11 reverted after this PR got merged. Just sent a PR #50834 to fix this.

PS: I think we should also add database test workflows for pgsql 10 and sqlsrv 2017 to Laravel 11 test suites.

[driesvints]

Thanks @hafezdivandari. I agree. I'll try to get that in.