run_external: remove inner quotes once nushell gets = sign (#13073)

# Description
Fixes: #13066

nushell should remove argument values' inner quote once it gets `=`.
Whatever it's a flag or not, and it also replace from `\"` to `"` before
passing it to external commands.

# User-Facing Changes
Given the shell script:
```shell
# test.sh
echo $@
```
## Before
```
>  sh test.sh -ldflags="-s -w" github.com
-ldflags="-s -w" github.com
> sh test.sh exp='-s -w' github.com
exp='-s -w' github.com
```
## After
```
>  sh test.sh -ldflags="-s -w" github.com
-ldflags=-s -w github.com
> sh test.sh exp='-s -w' github.com
exp=-s -w github.com
```

# Tests + Formatting
Added some tests

crates/nu-command/src/system/run_external.rs

@@ -218,14 +218,16 @@ impl Command for External {
 
 /// Removes surrounding quotes from a string. Doesn't remove quotes from raw
 /// strings. Returns the original string if it doesn't have matching quotes.
-fn remove_quotes(s: &str) -> &str {
+fn remove_quotes(s: &str) -> Cow<'_, str> {
     let quoted_by_double_quotes = s.len() >= 2 && s.starts_with('"') && s.ends_with('"');
     let quoted_by_single_quotes = s.len() >= 2 && s.starts_with('\'') && s.ends_with('\'');
     let quoted_by_backticks = s.len() >= 2 && s.starts_with('`') && s.ends_with('`');
-    if quoted_by_double_quotes || quoted_by_single_quotes || quoted_by_backticks {
-        &s[1..s.len() - 1]
+    if quoted_by_double_quotes {
+        Cow::Owned(s[1..s.len() - 1].to_string().replace(r#"\""#, "\""))
+    } else if quoted_by_single_quotes || quoted_by_backticks {
+        Cow::Borrowed(&s[1..s.len() - 1])
     } else {
-        s
+        Cow::Borrowed(s)
     }
 }
 
@@ -400,10 +402,6 @@ fn expand_glob(
 /// with double quotes, single quotes, or backticks. Only removes the outermost
 /// pair of quotes after the equal sign.
 fn remove_inner_quotes(arg: &str) -> Cow<'_, str> {
-    // Check that `arg` is a long option.
-    if !arg.starts_with("--") {
-        return Cow::Borrowed(arg);
-    }
     // Split `arg` on the first `=`.
     let Some((option, value)) = arg.split_once('=') else {
         return Cow::Borrowed(arg);
@@ -660,6 +658,7 @@ mod test {
         assert_eq!(remove_quotes(r#"`foo '"' bar`"#), r#"foo '"' bar"#);
         assert_eq!(remove_quotes(r#"'foo' bar"#), r#"'foo' bar"#);
         assert_eq!(remove_quotes(r#"r#'foo'#"#), r#"r#'foo'#"#);
+        assert_eq!(remove_quotes(r#""foo\" bar""#), r#"foo" bar"#);
     }
 
     #[test]
@@ -758,6 +757,18 @@ mod test {
         let actual = remove_inner_quotes(r#"--option "value""#);
         let expected = r#"--option "value""#;
         assert_eq!(actual, expected);
+
+        let actual = remove_inner_quotes(r#"-option="value""#);
+        let expected = r#"-option=value"#;
+        assert_eq!(actual, expected);
+
+        let actual = remove_inner_quotes(r#"option="value""#);
+        let expected = r#"option=value"#;
+        assert_eq!(actual, expected);
+
+        let actual = remove_inner_quotes(r#"option="v\"value""#);
+        let expected = r#"option=v"value"#;
+        assert_eq!(actual, expected);
     }
 
     #[test]

tests/shell/pipeline/commands/external.rs

@@ -590,4 +590,18 @@ mod external_command_arguments {
 
         assert_eq!(actual.out, "a;&$(hello)");
     }
+
+    #[test]
+    fn remove_quotes_in_shell_arguments() {
+        let actual = nu!("nu --testbin cococo expression='-r -w'");
+        assert_eq!(actual.out, "expression=-r -w");
+        let actual = nu!(r#"nu --testbin cococo expression="-r -w""#);
+        assert_eq!(actual.out, "expression=-r -w");
+        let actual = nu!("nu --testbin cococo expression='-r -w'");
+        assert_eq!(actual.out, "expression=-r -w");
+        let actual = nu!(r#"nu --testbin cococo expression="-r\" -w""#);
+        assert_eq!(actual.out, r#"expression=-r" -w"#);
+        let actual = nu!(r#"nu --testbin cococo expression='-r\" -w'"#);
+        assert_eq!(actual.out, r#"expression=-r\" -w"#);
+    }
 }