Upgrade unicode-width to 0.2

[KAAtheWiseGit]

unicode-width has to bundle unicode codepoint tables, so it's quite large (1.5MB). They've recently released the version 0.2, which caused a split in Nushell dependencies between 0.1 and 0.2, doubling the size.

The main breaking change for unicode-width is that \n is now counted as having width 1 and not 0. But that shouldn't matter for reedline, since the menus which use it (columnar/IDE/list) work on lines.

[sholderbach]

Sounds generally good to me, I remember that the changed semantics caused some serious churn for the tabled layouting.