Buffered container currently reallocates its backing texture every time it's resized

[peppy]

Noticed that in the blur transition to Player we have three textures which are constantly resizing. This is potentially causing a large amount of memory churn and potentially leading to performance issues for some users.

osu.2024-10-25.at.10.15.03.mp4

• We likely want to never shrink a backing textures so once they reach their largest usage, there is no overhead.
• We may want to also use power-of-two backing textures to reduce per-frame churn.