blur: issue master issue

[the-eater]

the new blur node has caused a few issues, so this is a small master issue to keep track:

• [x] Performance degradation for MangoWC Link - https://github.com/wlrfx/scenefx/pull/151
• [x] Blur randomly foreground, under unclear circumstances on container update Link Fix
• [x] Blur peeks underneath client-side corner radii surfaces Link (should be fixed, or give same behavior as previous revisions)

[the-eater]

can't assign myself, lol

[WillPower3309]

can't assign myself, lol

Gotchu