feat: allow formatting page title

[davidlj95]

Usually some pages want to format each page's title by either appending or prepending the site name. Separated by some separator. Like Foo page - Foo's site. Would be nice that the library allows to given the page name put the page title transparently according to a format. This way no need to call this formatter around. Just setting the page title is enough and the library will apply the proper format if a format has been configured.

[davidlj95]

Transformed to issue #1127 and closed by #1128