Classic Editor: Support pasted WebP image URLs in TinyMCE smart paste

[id7368]

Trac ticket: https://core.trac.wordpress.org/ticket/65734

Summary

This updates the bundled TinyMCE paste plugin so Classic Editor smart paste recognizes direct WebP image URLs and inserts them as images, matching the existing JPG/PNG/GIF URL behavior.

Why

WordPress supports WebP images, and current TinyMCE documents images_file_types as affecting which image URLs are recognized and placed in an img element by smart_paste. Its default list includes webp.

Testing

• Verified the minimal regex behavior on LC1:
  • .jpg, .jpeg, .png, .gif, .webp, and .WEBP image URLs are recognized.
  • .svg, query-string URLs, and non-absolute URLs keep the previous behavior.
• Ran JavaScript syntax checks for the modified TinyMCE paste plugin files on LC1.

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