Adding client cert common name(s) to the auth failure log

[mramezani95]

In case of auth failure due to untrusted client cert CNs, restapi currently generates the following message:

Authentication Fail! None of the common names in the client cert match any of the trusted common names

This PR adds client cert CNs to this log. This is useful for troubleshooting purposes.
This change was tested using an untrusted client cert. The following logs were generated as expected:

INFO restapi#supervisord: restapi [  info ] 2026/05/29 02:36:32 request: GET /v1/state/heartbeat StateHeartbeatGet
INFO restapi#supervisord: restapi [ error ] 2026/05/29 02:36:32 Authentication Failed! None of the common names in the client cert chain matched any of the trusted common names. Client cert common names: ["client.restapi.sonic"]
INFO restapi#supervisord: restapi [  info ] 2026/05/29 02:36:32 request: return 401
INFO restapi#supervisord: restapi [ error ] 2026/05/29 02:36:32 Request ends with error message {"error":{"code":401,"message":"Authentication Fail with untrusted client cert"}}

Note: This change was tested on the 202511 branch since the master branch has an auth issue: sonic-net/sonic-fips#86

[mssonicbld]

/azp run

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Azure Pipelines successfully started running 1 pipeline(s).

[qiluo-msft]

A peer presenting a CN like:

client.foo\n2026/05/29 02:36:32 INFO restapi#supervisord: restapi [ info ] Authentication succeeded

can forge a fake log entry in syslog, confuse SIEM line-parsers, or smuggle ANSI escapes into operator terminals tailing the log. This is CWE-117 / OWASP A09. The fix is one line — quote each CN before logging:

Suggested change

	commonNames = append(commonNames, peercert.Subject.CommonName)
	commonNames = append(commonNames, strconv.Quote(peercert.Subject.CommonName))

[mramezani95]

@qiluo-msft Fixed. Please review again.

[mssonicbld]

/azp run

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Azure Pipelines successfully started running 1 pipeline(s).