Fix#20230: Disable the discard button until Autosave is in progress.

[rahat2134]

Overview

1. This PR fixes or fixes part of #20230 .
2. This PR does the following:Disable the discard button until Autosave is in progress.Once Autosave is complete, the discard button will be reactivated for use.

   Essential Checklist

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• [X] I have linked the issue that this PR fixes in the "Development" section of the sidebar.
• [X] I have checked the "Files Changed" tab and confirmed that the changes are what I want to make.
• [X] I have written tests for my code.
• [X] The PR title starts with "Fix #bugnum: " or "Fix part of #bugnum: ...", followed by a short, clear summary of the changes.
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Proof that changes are correct

for desktop.webm

Proof of changes on mobile phone

mobile.webm

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[oppiabot[bot]]

Hi @rahat2134 please assign the required reviewer(s) for this PR. Thanks!

[rahat2134]

@Nik-09 PTAL,, #20203 is blocked due to this PR.

[oppiabot[bot]]

Unassigning @rahat2134 since a re-review was requested. @rahat2134, please make sure you have addressed all review comments. Thanks!

[rahat2134]

@Nik-09 PTAL, Have done requested changes.