Star icon too high on messages

[gnprice]

In the message list, when a message is starred, the star icon appears too high relative to the message text:

See chat thread for discussion.

Instead, the "shoulders" of the star (the near-horizontal top edges of the left and right wedges of the star) should be at about the x-height of the first line of text, i.e. about the same height as the top of letters like "x" and "e". Like this (from this PR subthread):

[PIG208]

A side by side comparison when the system font size changes using the configuration from #625 where the top inset of the star is set to 5.5 (originally 4):

This indicates that neither will work, because the insets do not scale with the text. Ideally we want to make sure the alignment is responsive regardless of the font size. So using a constant is likely not an ideal solution.