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/example_test.rs

@@ -209,10 +209,7 @@ mod test_examples {
         let mut stack = Stack::new();
 
         // Set up PWD
-        stack.add_env_var(
-            "PWD".to_string(),
-            Value::string(cwd.to_string_lossy(), Span::test_data()),
-        );
+        stack.add_env_var("PWD".to_string(), Value::test_string(cwd.to_string_lossy()));
 
         engine_state
             .merge_env(&mut stack, cwd)
@@ -294,10 +291,7 @@ mod test_examples {
 
         let mut stack = Stack::new();
 
-        stack.add_env_var(
-            "PWD".to_string(),
-            Value::string(cwd.to_string_lossy(), Span::test_data()),
-        );
+        stack.add_env_var("PWD".to_string(), Value::test_string(cwd.to_string_lossy()));
 
         match nu_engine::eval_block(engine_state, &mut stack, &block, input, true, true) {
             Err(err) => panic!("test eval error in `{}`: {:?}", "TODO", err),