feat: option to disable user pass based login (#18000)
* Added checkbox to disable pass login in settings
* Added user_pass disable option in Login page context
* Hide user-pass fields when option disabled
* Added check for social login key and LDAP
* feat: Disable API based usr-pwd login
* style: format with black
* refactor: simpify auth validation
No need for else clause
* refactor: fixup sys setting json and move field
* refactor: sys settings validation
* refactor: simpler imports
* chore: undo unintional changes
* test: add test for disabled user pass
Co-authored-by: Ankush Menat <ankush@frappe.io>