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/path/exists.rs

@@ -75,7 +75,7 @@ If you need to distinguish dirs and files, please use `path type`."#
             Example {
                 description: "Check if a file exists",
                 example: "'C:\\Users\\joe\\todo.txt' | path exists",
-                result: Some(Value::boolean(false, Span::test_data())),
+                result: Some(Value::test_bool(false)),
             },
             Example {
                 description: "Check if a file exists in a column",
@@ -91,7 +91,7 @@ If you need to distinguish dirs and files, please use `path type`."#
             Example {
                 description: "Check if a file exists",
                 example: "'/home/joe/todo.txt' | path exists",
-                result: Some(Value::boolean(false, Span::test_data())),
+                result: Some(Value::test_bool(false)),
             },
             Example {
                 description: "Check if a file exists in a column",