Update fragment_shared_decks_download.xml

[DevNishantHub]

Add a "Download Manually" Button in the Layout Add a button to the XML layout for the fragment. For example, in fragment_shared_decks_download.xml

Purpose / Description

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Fixes

• Fixes #

Approach

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How Has This Been Tested?

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Checklist

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• You have a descriptive commit message with a short title (first line, max 50 chars).
• You have commented your code, particularly in hard-to-understand areas
• You have performed a self-review of your own code
• UI changes: include screenshots of all affected screens (in particular showing any new or changed strings)
• UI Changes: You have tested your change using the Google Accessibility Scanner

[welcome]

First PR! 🚀 We sincerely appreciate that you have taken the time to propose a change to AnkiDroid! Please have patience with us as we are all volunteers - we will get to this as soon as possible.

[mikehardy]

Hi @DevNishantHub 👋 ! This is not a complete PR I don't think, based on the other two partial PRs also opened at nearly the same time, so I am converting this to a draft.

Please only propose complete PRs and include all the information requested in the PR template, thanks

[lukstbit]

Hey, thank you for trying to contribute.

For issue #17178 there's already an open PR(#17351) which was opened first and will most likely be merged as a fix.

As an alternative issue to contribute to there's #13282(please read the top post there) to get started with our codebase.