feat(cli): Introduce askForCursorPositionSync

[BlackAsLight]

Read (#6755) for an overview.

#6756 should be merged before this.

This function asks the terminal for the current position of the cursor. It is sync to prevent race conditions and its contents in complex in the hopes to guarantee reading the terminals response. It should not be used frequently as it does seem to introduce a noticeable delay, but in rare times the exact position of the cursor needs to be asked for.

This example is how it can be used but honestly using Ansi.saveCursorPosition and Ansi.restoreCursorPosition would have been much better and reliable.

import { Ansi } from "@std/cli/unstable-ansi";
import { askForCursorPositionSync } from "@std/cli/unstable-get-cursor";

const { column, row } = askForCursorPositionSync()!;
await Deno.stderr.write(new TextEncoder().encode(
  Ansi.setCursorPosition() +
    "Hello World!" +
    Ansi.setCursorPosition(row, column),
));

No tests as of yet have been written for this class as I don't know how to reliably check that its cursor position hasn't changed between writing and reading, especially with all the other tests also writing to the terminal.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.15%. Comparing base (fc59ca6) to head (f95ff2d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6757   +/-   ##
=======================================
  Coverage   94.14%   94.15%           
=======================================
  Files         586      586           
  Lines       42465    42465           
  Branches     6701     6701           
=======================================
+ Hits        39980    39983    +3     
+ Misses       2435     2433    -2     
+ Partials       50       49    -1     

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