Display empty records and lists (#7925)

# Description

Fix some issues related to #7444 
1. Empty lists and records are now displayed as a small notice in a box:

![image](https://user-images.githubusercontent.com/17511668/215832023-3f8d743a-2899-416f-9109-7876ad2bbedf.png)

![image](https://user-images.githubusercontent.com/17511668/215832273-c737b8a4-af33-4c16-8dd3-bd4f0fd19b5a.png)
2. Empty records are now correctly displayed if inside of another record
list or table:

![image](https://user-images.githubusercontent.com/17511668/215832597-00f0cebc-a3b6-4ce8-8373-a9340d4c7020.png)

![image](https://user-images.githubusercontent.com/17511668/215832540-ab0e2a14-b8f6-4f47-976c-42003b622ef6.png)
3. Fixed inconsistent coloring of empty list placeholder inside of
lists/tables:

![image](https://user-images.githubusercontent.com/17511668/215832924-813ffe17-e04e-4301-97c3-1bdbccf1825c.png)

![image](https://user-images.githubusercontent.com/17511668/215832963-4765c4cf-3036-4bcc-81e1-ced941fa47cb.png)


# User-Facing Changes

`table` command now displays empty records and lists like a table with
text and correctly displays empty records inside tables and lists.

New behavior of displaying empty lists and records can be disabled using
`table.show_empty` config option.

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

crates/nu-utils/src/sample_config/default_config.nu

@@ -187,6 +187,7 @@ let-env config = {
   table: {
     mode: rounded # basic, compact, compact_double, light, thin, with_love, rounded, reinforced, heavy, none, other
     index_mode: always # "always" show indexes, "never" show indexes, "auto" = show indexes when a table has "index" column
+    show_empty: true # show 'empty list' and 'empty record' placeholders for command output
     trim: {
       methodology: wrapping # wrapping or truncating
       wrapping_try_keep_words: true # A strategy used by the 'wrapping' methodology