Adding httpClientSessionInitv2 which through an argument will give the internal return code

[Gautham-coder]

Problem

httpClientSessionInit has its own set of status values it returns, but the actual rc/rsn of commands it does within are hidden behind compile-time printf statements.
This is unhelpful because this function does fail sometimes, and on zOS the reason is opaque and requires a GSK trace to then discover the cause. It just costs extra debug time then.

Proposed changes

Here we have httpClientSessionInit to httpClientSessionInitv2 to allow passing back internal rc. The original api still exists and calls the new version by passing a dummy argument.

This PR addresses Issue: #468

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

PR Checklist

Please delete options that are not relevant.

• If the changes in this PR are meant for the next release / mainline, this PR targets the "staging" branch.
• My code follows the style guidelines of this project (see: Contributing guideline)
• I have commented my code, particularly in hard-to-understand areas
• New and existing unit tests pass locally with my changes
• Relevant update to CHANGELOG.md
• My changes generate no new warnings

[JoeNemo]

Approved.