Accessibility: Add aria-live attribute support to `settings_errors()`

[himanshupathak95]

Trac ticket: https://core.trac.wordpress.org/ticket/63199

This PR enhances the accessibility of admin notices by adding support for the aria-live attribute in the settings_errors() function. This also adds the ability to control the aria-live attribute, which helps direct screen reader users' attention to these notices with appropriate urgency levels.

• Added an optional 'aria_live' parameter to add_settings_error()
• Updated settings_errors() to output the aria-live attribute when provided