Curve customization support: extract curve array from yaml and make a list of mapped number strings

[Gautham-coder]

Proposed changes 'zowe.network.server.tls.curves' is an array a user can set in zowe.yaml to customize crypto curves. GSK handles curves as a string of 4 digit numbers(IANA numbers) back to back without any spaces or symbols in between. Its very unfriendly to a human, so a mapping from names to numbers is needed, this is done in tls.h, for now only supported curves are in the array. Unsupported curves are commented and can be moved into this array as and when the supported curves are updated.

Curves are set during TLS settings initialization using gsk_attribute_set_buffer(), using 'GSK_CLIENT_ECURVE_LIST', see here https://www.ibm.com/docs/en/zos/3.1.0?topic=reference-gsk-attribute-set-buffer for reference,

Currently, the supported curves are here, https://www.ibm.com/docs/en/zos/3.1.0?topic=programming-cipher-suite-definitions#csdcwh__tttcsd

Testing: The curves that are not supported show an error in gsktrace as below, this was tested by adding some unsupported curves into the curve map array. ERROR set_binary_ecurves(): Elliptical curve 0001 not supported ERROR set_binary_ecurves(): Elliptical curve 0009 not supported ERROR set_binary_ecurves(): Elliptical curve 0026 not supported

To show the error in normal logs, only valid curves are in the mapping array. So if any invalid curve is mentioned in zowe.yaml an invalid curve message is logged.

zowe.network.server.tls.curves: ["x25519", "x448", "secp192r1", "secp224r1","prime256v1","secp384r1", "secp521r1"] , is converted to number string 0029003000190021002300240025

This PR addresses Issue: https://github.com/zowe/zss/issues/713

This PR depends on: https://github.com/zowe/zowe-common-c/pull/466

Type of change

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• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Change in a documentation
• [ ] Refactor the code
• [ ] Chore, repository cleanup, updates the dependencies.
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

PR Checklist

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• [x] If the changes in this PR are meant for the next release / mainline, this PR targets the "staging" branch.
• [x] My code follows the style guidelines of this project (see: Contributing guideline)
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [x] New and existing unit tests pass locally with my changes
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• [x] Relevant update to CHANGELOG.md
• [x] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works, or describe a test method below