Add Asciidoc Preview to WebIDE
Problem to solve
It's possible to edit certain markup files in WebIDE and view them in WYSIWYG form in file view ("Open in file view" in WebIDE). However, opening an edited file isn't very useful while editing because only the commited changes are in the WYSIWYG view. In the simple Edit editor there's Preview but not Review. It makes me wonder why there's no Preview in WebIDE because it seems to be meant to be more comprehensive than the Edit editor.
Intended users
Documentation writer
Further details
Use case: someone wants to make small edits to an .md or .adoc file with WebIDE. They want to compare the edited file with the original, but they also want to see the changes they are making in the live preview in the final formatted form before committing (like I can now do with this issue text by choosing "Preview").
Proposal
Add Preview to WebIDE. In the UI level it could be just a Preview tab next to the Edit tab above the document Edit view. Just like in this issue editor there are Write and Preview. It could also be added to the left side toolbar with Edit and Review. Clicking either Preview button/tab would activate both of them and change the document view to the preview mode.