Desktop Editor unification

[1000TurquoisePogs]

Dataset write support covered in #227 because it is the largest task.
MVS & USS Explorers in the Zowe Desktop have overlap with the Desktop's Editor but are maintained by same squad.
Build up the Editor so that missing featuers that are found in the MVS/USS Explorers are added to the Editor.
Editor will become a one-stop place for the out-of-the-box editing experience in the Desktop.

Deliverable

Specific features to be added include:

• Syntax highlighting for REXX (JCL and many other languages done already)
• File abilities: rename, cut, copy, paste, chmod, chown, chtag
• Dataset abilities: Write (requires locking), create, copy
• Adding/reorganizing hotkeys for existing and new features
• Adding any missing refresh abilities where missing
• Adding any missing progress indicators when loading
• hoverhelp (rexx, jcl)

NOTE: USS & MVS explorers will still be bundled as they should not be removed during an LTS.

Dependency

None?

Risk

Hoverhelp not yet researched. Feature completion will depend upon library capabilities.

[1000TurquoisePogs]

Additional concerns identified:
explorer uis are sometimes used for embedding in iframe. Can editor do the same for the same people?
single app mode of the app fw can be used for embedding, but unsure if that meets the same needs.

[1000TurquoisePogs]

It would be a great idea to add a size check and warning against opening extra large datasets

[1000TurquoisePogs]

I'm going to close this because all work except hoverhelp has been done. We will open up a hoverhelp ticket specifically.