Improve performance of file uploads

[markcocker]

Improve the performance of uploading files via the zowe cics-deploy push bundle CLI by adding an option equivalent to --max-concurrent-requests to increase the number of concurrent file uploads.

As an example, if I deploy the cics-nodejs-invoke example that consists of 68 files totalling 12.5MB in size it took 4mins minutes, most of that time was spent uploading files.

So I then tried using zowe zos-files upload dir-to-uss "." "/u/cockerm/test" --recursive to upload the files and it took:

• 2:31mins.
• 1:28 mins when adding option --max-concurrent-requests 2
• 1:08mins when adding option --max-concurrent-requests 4

I also tried export ZOWE_OPT_MAX_CONCURRENT_REQUESTS=0 before zowe cics-deploy push bundle but this did not work.