MVS for FTP package

[lauren-li]

Is your feature request related to a problem? Please describe.
During Zowe Explorer development, it is possible for contributors to make changes that break extenders without realizing it. Adding MVS to the FTP package would give more Zowe Explorer contributors the ability to manually test their changes in the context of extenders. This would allow the Zowe Explorer squad as a whole to develop more efficiently while lowering risk of unintentionally breaking extenders.
This feature has also previously been requested by users. (See related issues.)

Describe the solution you'd like
Add MVS capabilities to the FTP package

Additional context
Related issues:
Issue #994 and zowe/zowe-explorer-ftp-extension#10 (Allow Zowe Explorer to function without OSMF, by instead using zos-ftp-for-zowe-cli plugin)