Further cleanup of Span::test_data usage + span fixes (#7595)

# Description

Inspired by #7592

For brevity use `Value::test_{string,int,float,bool}`

Includes fixes to commands that were abusing `Span::test_data` in their
implementation. Now the call span is used where possible or the explicit
`Span::unknonw` is used.

## Command fixes
- Fix abuse of `Span::test_data()` in `query_xml`
- Fix abuse of `Span::test_data()` in `term size`
- Fix abuse of `Span::test_data()` in `seq date`
- Fix two abuses of `Span::test_data` in `nu-cli`
- Change `Span::test_data` to `Span::unknown` in `keybindings listen`
- Add proper call span to `registry query`
- Fix span use in `nu_plugin_query`
- Fix span assignment in `select`
- Use `Span::unknown` instead of `test_data` in more places

## Other
- Use `Value::test_int`/`test_float()` consistently
- More `test_string` and `test_bool`
- Fix unused imports


# User-Facing Changes

Some commands may now provide more helpful spans for downstream use in
errors

crates/nu-command/src/strings/encode_decode/base64.rs

@@ -249,7 +249,7 @@ mod tests {
 
     #[test]
     fn base64_decode_binhex() {
-        let word = Value::string("A5\"KC9jRB@IIF'8bF!", Span::test_data());
+        let word = Value::test_string("A5\"KC9jRB@IIF'8bF!");
         let expected = Value::binary(b"a binhex test".as_slice(), Span::test_data());
 
         let actual = action(
@@ -272,7 +272,7 @@ mod tests {
 
     #[test]
     fn base64_decode_binhex_with_new_line_input() {
-        let word = Value::string("A5\"KC9jRB\n@IIF'8bF!", Span::test_data());
+        let word = Value::test_string("A5\"KC9jRB\n@IIF'8bF!");
         let expected = Value::binary(b"a binhex test".as_slice(), Span::test_data());
 
         let actual = action(

crates/nu-command/src/strings/encode_decode/encode_base64.rs

@@ -2,7 +2,7 @@ use super::base64::{operate, ActionType, CHARACTER_SET_DESC};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
+    Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -54,7 +54,7 @@ impl Command for EncodeBase64 {
             Example {
                 description: "Encode a string with the binhex character set",
                 example: "'Some Data' | encode base64 --character-set binhex",
-                result: Some(Value::string(r#"7epXB5"%A@4J"#, Span::test_data())),
+                result: Some(Value::test_string(r#"7epXB5"%A@4J"#)),
             },
         ]
     }