Additional image file size optimization

[Awqre]

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• [X] My contribution is not related to translations.
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Description

I noticed Signal's recent effort to reduce file size which is much appreciated as some don't realize how even the smallest reduction has meaningful impact long term. I have run the repo and asset images through some programs and losslessly reduced the file size by small amounts.

PNG: zopflipng/ECT/deflopt APNG: same as above, repacked with apngasm jpg: ECT