Fix issue with zoom behaviour of PDF being inconsistent in Safari mobile

[eVoloshchak]

Details

inconsistent behaviour was caused by Dimensions 'change' listener returning invalid window sizes when zooming in or out.
We've settled on using pdf container's width to determine the page width.

Fixed Issues

$ #4867

Tests

1. run npm run web
2. navigate to any chat that has a pdf attachment
3. click on pdf attachment to open it
4. zoom in as close as possible, zoom out
5. validate that zoom is consistent and layout isn't changing

QA Steps

Same as Tests

Tested On

• Web
• Mobile Web
• Desktop
• iOS
• Android

Screenshots

Device: iPhone X
OS: iOS 14.7.1

vert.mp4

horiz.mp4

[github-actions]

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[eVoloshchak]

Closing this due to a problem with my git configuration, my bad.
Opened a new PR