reduce the `\e[6n` spam to improve high-ping ssh scenarios

[Jan9103]

currently reedline sends a \e[6n to the terminal after every redraw (pressing any key).
this causes reedline to block until it gets the cursor-position back from the terminal.

lets say you have a 500ms ping (Geo-stationary satellite internet, cross-continent, etc):

1. you send a single keypress lets say a
2. 500ms: pass and it arrives at the server
3. 1sec: reedline requests the cursor position (\e[6n)
   1. 500ms your terminal receives the request
   2. 500ms reedline recieves the response
4. 500ms: reedline sends the updates to your terminal

so it takes 2 seconds to render 1 character change.. and half of it is caused by the cursor-position-request.

i found this by running nu via ^nu | ^tee test.bin and checking test.bin after every key-press in a separate terminal.

References

discussions about reedline being slow over ssh:

• Performance issue for repeated key presses when using reedline through a slow ssh connection #914
• https://discord.com/channels/601130461678272522/614593951969574961/1431608904009388042
• https://discord.com/channels/601130461678272522/614593951969574961/1409160306256511030