Fix find command output bug in the case of taking ByteStream input. (#13246)

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fixes #13245 

# Description
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In addition to addressing #13245, this PR also updated one of the doc
example to the `find` command to document that non-regex mode is case
insensitive, which may surprise some users.

# User-Facing Changes
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---------

Co-authored-by: Ben Yang <ben@ya.ng>
Co-authored-by: Darren Schroeder <343840+fdncred@users.noreply.github.com>

crates/nu-command/src/filters/find.rs

@@ -69,9 +69,9 @@ impl Command for Find {
                 result: None,
             },
             Example {
-                description: "Search and highlight text for a term in a string",
-                example: r#"'Cargo.toml' | find toml"#,
-                result: Some(Value::test_string("\u{1b}[37mCargo.\u{1b}[0m\u{1b}[41;37mtoml\u{1b}[0m\u{1b}[37m\u{1b}[0m".to_owned())),
+                description: "Search and highlight text for a term in a string. Note that regular search is case insensitive",
+                example: r#"'Cargo.toml' | find cargo"#,
+                result: Some(Value::test_string("\u{1b}[37m\u{1b}[0m\u{1b}[41;37mCargo\u{1b}[0m\u{1b}[37m.toml\u{1b}[0m".to_owned())),
             },
             Example {
                 description: "Search a number or a file size in a list of numbers",
@@ -457,9 +457,10 @@ fn find_with_rest_and_highlight(
 
                 let mut output: Vec<Value> = vec![];
                 for line in lines {
-                    let line = line?.to_lowercase();
+                    let line = line?;
+                    let lower_val = line.to_lowercase();
                     for term in &terms {
-                        if line.contains(term) {
+                        if lower_val.contains(term) {
                             output.push(Value::string(
                                 highlight_search_string(
                                     &line,

crates/nu-command/tests/commands/find.rs

@@ -17,6 +17,16 @@ fn find_with_list_search_with_char() {
     assert_eq!(actual.out, "[\"\\u001b[37m\\u001b[0m\\u001b[41;37ml\\u001b[0m\\u001b[37marry\\u001b[0m\",\"\\u001b[37mcur\\u001b[0m\\u001b[41;37ml\\u001b[0m\\u001b[37my\\u001b[0m\"]");
 }
 
+#[test]
+fn find_with_bytestream_search_with_char() {
+    let actual =
+        nu!("\"ABC\" | save foo.txt; let res = open foo.txt | find abc; rm foo.txt; $res | get 0");
+    assert_eq!(
+        actual.out,
+        "\u{1b}[37m\u{1b}[0m\u{1b}[41;37mABC\u{1b}[0m\u{1b}[37m\u{1b}[0m"
+    )
+}
+
 #[test]
 fn find_with_list_search_with_number() {
     let actual = nu!("[1 2 3 4 5] | find 3 | get 0");