[8.x](backport #40978) x-pack/filebeat/input/azureblobstorage: add support for CSV decoding

[mergify]

Proposed commit message

The test file txn.csv.gz was obtained from https://netskopepartnerlogfilebucket.s3.amazonaws.com/txn-1722875066329034-fe10b6a23cc643c4b282e6190de2352d.csv.gz

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Disruptive User Impact

Author's Checklist

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How to test this PR locally

Related issues

• For [Netskope] Test ingestion of compressed Netskope cloud storage logs integrations#10744

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This is an automatic backport of pull request #40978 done by [Mergify](https://mergify.com).

[botelastic]

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[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b mergify/bp/8.x/pr-40978 upstream/mergify/bp/8.x/pr-40978
git merge upstream/8.x
git push upstream mergify/bp/8.x/pr-40978