Update the Secrets SDK bundled with Zowe CLI V2

[t1m0thyj]

The Secrets SDK on the V2 branch (v7.x) has not been updated in a few years. It has fallen behind the V3 branch (v8.x) which has received patches and security fixes.

So long as there are no breaking changes between v7.x and v8.x of the Secrets SDK, we could bundle the latest version with both Zowe CLI V2 and V3. We already do similar with the Zowe daemon in the zowex directory.

[github-actions]

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