fix(security): prevent SQL injection in tax controller sort columns

Add sanitizeSortColumn() validation to prevent SQL injection in the
sort parameter of search() methods in tax-related controllers.

Vulnerable controllers:
- Taxes.php: sort column was passed directly to model
- Tax_categories.php: sort column was passed directly to model
- Tax_codes.php: sort column was passed directly to model
- Tax_jurisdictions.php: sort column was passed directly to model

Fix: Use sanitizeSortColumn() to validate sort column against
allowed headers, defaulting to primary key if invalid.
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f