Add challenge password to CSR Development

[rgqsch]

Description

New code based on an older PR, fixed to latest coding styles. This will add a challenge password to the CSR which might be needed by some SCEP servers

PR checklist

Please remove the segment/s on either side of the | symbol as appropriate, and add any relevant link/s to the end of the line. If the provided content is part of the present PR remove the # symbol.

• [ ] changelog provided In this PR
• [ ] development PR provided | In this PR
• [ ] TF-PSA-Crypto PR not required because: Not changed
• [ ] framework PR provided Mbed-TLS/mbedtls-framework#219
• [ ] 3.6 PR provided #10432
• tests provided In this PR

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[mpg]

Hi and thanks for your contribution!

New code based on an older PR, fixed to latest coding styles.

Thanks for the update! Could you provide a link to the older PR? In case it already had some review history.

[rgqsch]

Hi and thanks for your contribution!

New code based on an older PR, fixed to latest coding styles.

Thanks for the update! Could you provide a link to the older PR? In case it already had some review history.

There were 2 old PR, those were never merged (#7843 and #7444 ). This is a complete rewrite trying to be more generic: In mbedtls_x509write_csr adding a generic attributes field, in stead of a dedicated csr_password field.