Use big type for page titles

Currently our breadcrumbs are divided in two lines (global and contextual). With #35121 (closed) we will combine both breadcrumbs, leaving the the title of the page as the last element of the line.

@pedroms proposed we keep the last element in the second line, but increasing its size so it really acts as a title for the page. I think this is an interesting proposal as it really emphasizes where you are located. It does increase the size of the breadcrumbs, but since it is a scrollable element I don't think it should be a problem.

I created some mockups aligning the text and elements to the 8px grid and using the sizes from the type ramp.

For the Issue/MR page we can include the status, timestamp and author in the breadcrumbs bar. @pedroms's origina proposal was to include the issue title in this line instead of the issue number, but I decided agains it because it led to arbitrary height of the breadcrumbs bar depending on the issue title's length, as well as difficulties in aligning the action buttons on the right.

For the project page we can use the breadcrumbs bar to replace the current header, which users have complained takes up too much vertical space.

What do you think @tauriedavis @hazelyang @dimitrieh @sarrahvesselov?