Implement in-app titlebar and esc to go back

[MarcAnt01]

Currently the titlebar has a hacky back button that is a bit too small for touch targets and isn't consistent with apps like snipping tool using an in-app titlebar.
It's also necessary to implement esc to go back functionality

[JaiganeshKumaran]

Instead of duplicating the custom title bar in each top-level page, have a single top-level page and show the separate pages inside a frame under the page. Most apps do it this way so you get the same title bar.

[MarcAnt01]

Hey @JaiganeshKumaran , I totally lost this message, now there's a proper in-app titlebar button (from 3.0 branch), while esc to go back still has to be implemented.
If you think that having a top level page is better, feel free to send a pr, anyway consider that the back button is needed only in some pages, while in others it shouldn't be there