[ui-storagebrowser] fixes the preview for non-text files

[ramprasadagarwal]

What changes were proposed in this pull request?

• When a file with an unsupported extension (e.g., Dockerfile) was opened in the file browser, a message indicating "unsupported file type" was shown, which prevented users from viewing the content of the file, even if it contained readable text.
• Fix: Adjusted the logic to allow users to view the file content, regardless of unsupported extensions, if the file contains readable text.

How was this patch tested?

• Updated the unit tests

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