Enable shell_integration.osc9_9 by default on Windows (#15914)

# Description

This sets the value to true by default only on Windows. This is not a
legacy code and is used by the Windows Terminal to detect the current
directory (explicitly enabling osc7 did not work). Here are the official
docs:
https://learn.microsoft.com/en-us/windows/terminal/tutorials/new-tab-same-directory

# User-Facing Changes

Windows users will by default have their terminals properly detect the
current working directory without extra configuration/troubleshooting.

crates/nu-protocol/src/config/shell_integration.rs

@@ -17,9 +17,9 @@ impl Default for ShellIntegrationConfig {
     fn default() -> Self {
         Self {
             osc2: true,
-            osc7: true,
+            osc7: !cfg!(windows),
             osc8: true,
-            osc9_9: false,
+            osc9_9: cfg!(windows),
             osc133: true,
             osc633: true,
             reset_application_mode: true,

crates/nu-utils/src/default_files/doc_config.nu

@@ -202,11 +202,13 @@ $env.config.shell_integration.osc2 = true
 # osc7 (bool):
 # Nushell will report the current directory to the terminal using OSC 7. This is useful when
 # spawning new tabs in the same directory.
+# This is disabled by default on Windows in favor of the `osc9_9` option.
 $env.config.shell_integration.osc7 = true
 
 # osc9_9 (bool):
 # Enables/Disables OSC 9;9 support, originally a ConEmu terminal feature. This is an
 # alternative to OSC 7 which also communicates the current path to the terminal.
+# This is enabled by default on Windows as it is used by the Windows Terminal.
 $env.config.shell_integration.osc9_9 = false
 
 # osc8 (bool):