[NavigationBar] Vertically center navigationBar title within its default height for UIControlContentVerticalAlignmentTop (#1576)
[NavigationBar] Vertically center navigationBar title within its default height for UIControlContentVerticalAlignmentTop (#1576)

* Update MDCNavigationBar titleVerticalAlignment to Center

Since MDCNavigationBar is now using the iOS back button style, it doesn't look right to top alignment the title label. Update this -layoutSubviews implementation to use UIControlContentVerticalAlignmentCenter instead.

* Vertically center navigationBar title within default height

When UIControlContentVerticalAlignment is Top, still center it vertically within the default navigationBar height

* Set originY to 0 if title height is larger than navigation bar

* Add comment for back button vertically centered

When using UIControlContentVerticalAlignmentTop, vertically center to back button

samnm/material-components-ios,randallli/material-components-ios,sigito/material-components-ios,randallli/material-components-ios,Eccelor/material-components-ios,randallli/material-components-ios,randallli/material-components-ios,sigito/material-components-ios,sigito/material-components-ios,brianjmoore/material-components-ios,Eccelor/material-components-ios,brianjmoore/material-components-ios,samnm/material-components-ios,Eccelor/material-components-ios,material-components/material-components-ios,samnm/material-components-ios,willlarche/material-components-ios,brianjmoore/material-components-ios,randallli/material-components-ios,Eccelor/material-components-ios,material-components/material-components-ios,Eccelor/material-components-ios,samnm/material-components-ios,randallli/material-components-ios,willlarche/material-components-ios,material-components/material-components-ios,brianjmoore/material-components-ios,material-components/material-components-ios,willlarche/material-components-ios,samnm/material-components-ios,brianjmoore/material-components-ios,sigito/material-components-ios,willlarche/material-components-ios,sigito/material-components-ios,material-components/material-components-ios,willlarche/material-components-ios