increase maximum description lenght in UI

[isopod-a]

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Contributor checklist

• [ X ] I am following the Code Style Guidelines
• [ X ] I have tested my contribution on these devices:

• Motorola moto e13, Android 13

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• [ X ] I ensure that all the open issues my contribution fixes are mentioned in the commit message of my first commit using the Fixes #1234 syntax

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Description

In the UI input, the number of glyphs is currently limited to 480 (with 8k max bytes). For larger groups with guidelines, more space is needed.
This patch increases the number of glyphs and bytes by a factor of eight to 3840 and 65536.
Signal community feature request: https://community.signalusers.org/t/expand-the-group-chat-description-or-pin-posts/65179
On the test device a group description of new maximum length could be set and it could be viewed by other devices running the official release.

Equivalent implementation for iOS at isopod-a/Signal-iOS@6232ee7
and for Desktop client at isopod-a/Signal-Desktop@bdf40f4