Panes have an additional header when dragging them from a tab

[kdinev]

Description

When undock (start dragging) a docked pane in a tab, the floating pane has two headers.

• version: 1.7.0
• browser: all

Steps to reproduce

1. Open https://www.infragistics.com/products/ignite-ui-angular/angular/components/dock-manager
2. Start dragging "Document 2"

Result

The "Document 2" pane has two headers.

Expected result

There should be only one header

Attachments

[onlyexeption]

When rendering a floating pane, a pane header gets rendered on top of it so we can handle the whole document host dragging/closing. If we remove it, we should either change the tabs component so it can support drag events or change the pane header to support rendering tab headers inside it. Since both scenarios will require a lot of changes, testing and potential introduction of bugs, here's a proposition that wouldn't require any big changes but will still resolve this issue.

1. Remove the maximize icon from the tab strip area.
2. Display the active pane's name in the pane header.
3. Add margin around the split pane.

FYI, VS has a similar way of handling this scenario:

@kdinev, @sdimchevski let me know what you think.