Fix shimmer in dark mode and also add it on profile feed

[Palakkgoyal]

This PR closes #1082
I have fixed the shimmer effect on darkmode and also added in on the profile feed.

[github-actions]

Thank you Palakkgoyal! for creating this pull request and contributing to Dummygram! 💗

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We appreciate your patience and contribution, Keep up the great work! 😀

[narayan954]

Hi @Palakkgoyal there seems to be repetition of lots of code, if it seems feasible,can you try something like

function FeedSkeleton() {
  const numSkeletons = 4;

  return (
    <>
      {Array.from({ length: numSkeletons }, (_, index) => (
        <Skeleton
          key={index}
          variant="rectangular"
          style={{
            width: "100%",
            height: "100%",
            aspectRatio: "1",
          }}
          className="shimmer_bg"
        />
      ))}
    </>
  );
}

[Palakkgoyal]

Yes, sure. I will fix that.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
2 Code Smells

No Coverage information
0.0% Duplication

[narayan954]

looks good to me!