support blink cursor, and fix underscore's cursorshape

[WindSoilder]

Description

Close: #8988

Thanks to new crossterm version, nushell can support blink cursor shape. It can be config with the following value:

1. blink_block
2. blink_line
3. blink_underscore

And original block, line, underscore will be steady. It also fixes wrong shape of underscore.

User-Facing Changes

Here is a little breaking change, before the change: line cursor shape is blinking line, but after this pr, it will be steady line. To make a blink line, we need to change the value to blink_line.

But I think it's ok, because after the change, we have a good naming convention about the name of shape

Tests + Formatting

After Submitting

[fdncred]

nice! I wonder if these additional ones were introduced with crossterm 26 or we just missed them the first time?

[WindSoilder]

Yeah, they are introduced with crossterm 26. We didn't miss them before

[amtoine]

is it normal that this should close #8988 but #8988 is already closed? 😮

[WindSoilder]

Not really :-) @fdncred provides a good solution for that issue. But the pr provides another way to do this

[fdncred]

Thanks. As always, good job!

[amtoine]

@WindSoilder gotcha, thanks 😋