[IBGBUGCHAT-10593] support certificate content type

[smohamedinstabug]

Problem:

file command considers the pem files as “text/plain” and mimemagic can't detect the pem files content type

Solution:

Try to open a file with OpenSSL::X509::Certificate. so If the file opened successfully, it will be a pem file.

Notes:

TODO: anything that reviewers should know before reviewing?

QC Notes:

TODO: What parts/flows of the app are affected by this change?

Release steps:

TODO: steps needed for the release. If no special handling needed, please write 'Normal Release'

Security:

TODO: Are the changes exposed publicly or internally?

TODO: Do all new endpoints impose proper access to authorized users only?

Network:

TODO: Link to Ops PR if any. Type N/A if none.

TODO: List new internal/external services communications that were introduced in this PR. Type N/A if none.

Author checklist:

• Backward compatibility checked
• Release steps added
• Unit tests added (if code logic is touched)
• JIRA ticket moved to Reviewing
• Rebased to latest master
• Commits are clean

Reviewer checklist:

• Backward compatibility checked
• Code quality is acceptable
• Specs logic coverage
• Commits are clean