Move [DiagTail.[DefaultInnerRadius]] from letter/shared.ptl to meta/aesthetics.ptl.

[jmcwilliams403]

This saves an import in letter/latin/v.ptl and letter/latin/w.ptl.

Also further code cleanup in the surrounding files.

Effectively nothing is changed otherwise, although there might be some incidental improvements of floating point rounding by simplifying some of the math with some of the additional code cleanup in letter/latin/v.ptl, particularly for Lower V with Curl (ⱴ).

[be5invis]

I think isolating DiagTail-specific parameters into separate files is good for organizing things.

Actually I somehow want to move some of the parameters out from meta/aesthetics.ptl, and put them into the corresponded functions.

[jmcwilliams403]

Compromise: How about we only move [DefaultInnerRadius] out? The cursive w/v shapes have little to do with a literal diagonal tail but still use this specific metric.

[be5invis]

You can rename it to DefaltTightBendInnerRadius