Formatting: Convert multiplication symbol to 'x' in title slugs

[himanshupathak95]

Trac ticket: https://core.trac.wordpress.org/ticket/64284

This PR ensures the multiplication symbol (×) and its HTML entities are consistently replaced with the letter "x" when sanitizing titles for slugs.

Users sometimes accidentally type × (U+00D7, Multiplication Sign) instead of x (U+0078, Latin Small Letter X) in post titles. The existing code only replaced the URL-encoded form (%c3%97) after encoding, which didn't handle the character consistently in all cases.

This PR adds replacement of the multiplication character and its entities before URL encoding occurs:

• Direct character: ×
• HTML entity: ×
• Numeric entity: ×

The existing replacement of %c3%97 (line 2387) is retained as a fallback for already-encoded content.

Examples

Input	Output
iPhone 12 × 256GB	iphone-12-x-256gb
Screen 1920 × 1080	screen-1920-x-1080
6×7 is 42	6x7-is-42
Product 5×10	product-5x10