Revise tests for certificate authentication on ssh agents (#231)

* HttpRequestStepCredentialsTest: use prettier random *.p12 temporary file names [JENKINS-70101]

Signed-off-by: Jim Klimov <jimklimov+jenkinsci@gmail.com>

* HttpRequestStepCredentialsTest: update some javadocs, move code under shared property declarations and group test-case families [JENKINS-70101]

Signed-off-by: Jim Klimov <jimklimov+jenkinsci@gmail.com>

* HttpRequestStepCredentialsTest: cpsScriptCredentialTestHttpRequest(): refactor to use verbosePipelines test class property [JENKINS-70101]

Signed-off-by: Jim Klimov <jimklimov+jenkinsci@gmail.com>

* HttpRequestStepCredentialsTest: cpsScriptCredentialTestHttpRequest(): refactor to optionally juggle withReentrability and to debug-trace withLocalCertLookup [JENKINS-70101]

Import and adapt code evicted from jenkinsci/credentials-plugin#391

Signed-off-by: Jim Klimov <jimklimov+jenkinsci@gmail.com>

* HttpRequestStepCredentialsTest: refactor existing testCert*() to use updated cpsScriptCredentialTestHttpRequest() helper, and import their siblings from credentials-plugin#391 [JENKINS-70101]

Signed-off-by: Jim Klimov <jimklimov+jenkinsci@gmail.com>

* HttpRequestStepCredentialsTest: cpsScriptCredentialTestHttpRequest() helper: make use of runnerTag argument [JENKINS-70101]

Signed-off-by: Jim Klimov <jimklimov+jenkinsci@gmail.com>

* HttpRequestStepCredentialsTest: cpsScriptCredentialTestHttpRequest() helper: report cred ID if drilling withLocalCertLookup [JENKINS-70101]

Signed-off-by: Jim Klimov <jimklimov+jenkinsci@gmail.com>

* HttpRequestStepCredentialsTest: import tests and helper code to (optionally) verify that credentials pass over to remote agents correctly [JENKINS-70101]

Signed-off-by: Jim Klimov <jimklimov+jenkinsci@gmail.com>

* HttpRequestStepCredentialsTest: use the simpler form of Class.forName(), it seems to be more reliable [JENKINS-70101]

Signed-off-by: Jim Klimov <jimklimov+jenkinsci@gmail.com>

* Do not duplicate words in debug output

First First HTTP Request -> First HTTP Request

Fixes #231 (comment)

* Switch modifier order for consistency

Fixes #231 (comment)

* Retain default crumb issuer behavior

Fixes #231 (comment)

* Make javadoc match test implementation

Fixes #231 (comment)

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Signed-off-by: Jim Klimov <jimklimov+jenkinsci@gmail.com>
Co-authored-by: Mark Waite <mark.earl.waite@gmail.com>

Author: jimklimov