Fix incomplete files when downloading data sets

[t1m0thyj]

What It Does

Fixes #744

How to Test

• Test that the issue with downloading small data sets using BufferBuilder is fixed:

const { BufferBuilder, ProfileInfo } = require("@zowe/imperative");
const { Download } = require("@zowe/zos-files-for-zowe-sdk");

(async () => {
    // Load connection info from default z/OSMF profile
    const profInfo = new ProfileInfo("zowe");
    await profInfo.readProfilesFromDisk();
    const zosmfProfAttrs = profInfo.getDefaultProfile("zosmf");
    const zosmfMergedArgs = profInfo.mergeArgsForProfile(zosmfProfAttrs, { getSecureVals: true });
    const session = ProfileInfo.createSession(zosmfMergedArgs.knownArgs);
    const stream = new BufferBuilder();
    const response = await Download.dataSet(session, "SYS1.MACLIB(ABEND)", {stream});
    console.log(stream.read());
})();

• Test that there is no regression in cross-LPAR copy related to Fix for request steam failure imperative#1022
  zowe files copy dsclp <sourceDsname> <targetDsname> --target-zosmf-profile <profileName>
  where the source dsname points to a large sequential DS (>16KB)

Review Checklist
I certify that I have:

• tested my changes
• added/updated automated tests
• updated the changelog
• followed the contribution guidelines

Additional Comments

Thanks to @traeok for his BufferBuilder implementation in Zowe Explorer 😋

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.14%. Comparing base (770478c) to head (6f4f5e6).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2167   +/-   ##
=======================================
  Coverage   91.13%   91.14%           
=======================================
  Files         636      637    +1     
  Lines       19054    19064   +10     
  Branches     3901     3900    -1     
=======================================
+ Hits        17365    17376   +11     
+ Misses       1688     1687    -1     
  Partials        1        1           

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[traeok]

Thanks for the fix Timothy, LGTM

[anaxceron]

Just made one small comment -- looks good @t1m0thyj

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[github-actions]

Release succeeded for the master branch. 🎉

The following packages have been published:

• npm: @zowe/imperative@5.24.0
• npm: @zowe/zos-files-for-zowe-sdk@7.26.0
• npm: @zowe/zos-workflows-for-zowe-sdk@7.26.0
• npm: @zowe/zos-jobs-for-zowe-sdk@7.26.0
• npm: @zowe/cli@7.26.0

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