REFACTOR: move the 0% commands to nu-cmd-extra (#9404)

requires
- https://github.com/nushell/nushell/pull/9455

# ⚙️ Description
in this PR i move the commands we've all agreed, in the core team, to
move out of the core Nushell to the `extra` feature.

> **Warning**
> in the first commits here, i've
> - moved the implementations to `nu-cmd-extra`
> - removed the declaration of all the commands below from `nu-command`
> - made sure the commands were not available anymore with `cargo run --
-n`

## the list of commands to move
with the current command table downloaded as `commands.csv`, i've run
```bash
let commands = (
    open commands.csv
    | where is_plugin == "FALSE" and category != "deprecated"
    | select name category "approv. %"
    | rename name category approval
    | insert treated {|it| (
        ($it.approval == 100) or                # all the core team agreed on them
        ($it.name | str starts-with "bits") or  # see https://github.com/nushell/nushell/pull/9241
        ($it.name | str starts-with "dfr")      # see https://github.com/nushell/nushell/pull/9327
    )}
)
```
to preprocess them and then
```bash
$commands | where {|it| (not $it.treated) and ($it.approval == 0)}
```
to get all untreated commands with no approval, which gives
```
╭────┬───────────────┬─────────┬─────────────┬──────────╮
│  # │     name      │ treated │  category   │ approval │
├────┼───────────────┼─────────┼─────────────┼──────────┤
│  0 │ fmt           │ false   │ conversions │        0 │
│  1 │ each while    │ false   │ filters     │        0 │
│  2 │ roll          │ false   │ filters     │        0 │
│  3 │ roll down     │ false   │ filters     │        0 │
│  4 │ roll left     │ false   │ filters     │        0 │
│  5 │ roll right    │ false   │ filters     │        0 │
│  6 │ roll up       │ false   │ filters     │        0 │
│  7 │ rotate        │ false   │ filters     │        0 │
│  8 │ update cells  │ false   │ filters     │        0 │
│  9 │ decode hex    │ false   │ formats     │        0 │
│ 10 │ encode hex    │ false   │ formats     │        0 │
│ 11 │ from url      │ false   │ formats     │        0 │
│ 12 │ to html       │ false   │ formats     │        0 │
│ 13 │ ansi gradient │ false   │ platform    │        0 │
│ 14 │ ansi link     │ false   │ platform    │        0 │
│ 15 │ format        │ false   │ strings     │        0 │
╰────┴───────────────┴─────────┴─────────────┴──────────╯
```
# 🖌️ User-Facing Changes
```
$nothing
```

# 🧪 Tests + Formatting
- ⚫ `toolkit fmt`
- ⚫ `toolkit clippy`
- ⚫ `toolkit test`
- ⚫ `toolkit test stdlib`

# 📖 After Submitting
```
$nothing
```

# 🔍 For reviewers
```bash
$commands | where {|it| (not $it.treated) and ($it.approval == 0)} | each {|command|
    try {
        help $command.name | ignore
    } catch {|e|
        $"($command.name): ($e.msg)"
    }
}
```
should give no output in `cargo run --features extra -- -n` and a table
with 16 lines in `cargo run -- -n`

crates/nu-cmd-base/src/formats/mod.rs

@@ -0,0 +1 @@
+pub mod to;

crates/nu-cmd-base/src/formats/to/delimited.rs

@@ -0,0 +1,20 @@
+use indexmap::{indexset, IndexSet};
+use nu_protocol::Value;
+
+pub fn merge_descriptors(values: &[Value]) -> Vec<String> {
+    let mut ret: Vec<String> = vec![];
+    let mut seen: IndexSet<String> = indexset! {};
+    for value in values {
+        let data_descriptors = match value {
+            Value::Record { cols, .. } => cols.to_owned(),
+            _ => vec!["".to_string()],
+        };
+        for desc in data_descriptors {
+            if !desc.is_empty() && !seen.contains(&desc) {
+                seen.insert(desc.to_string());
+                ret.push(desc.to_string());
+            }
+        }
+    }
+    ret
+}

crates/nu-cmd-base/src/formats/to/mod.rs

@@ -0,0 +1 @@
+pub mod delimited;

crates/nu-cmd-base/src/lib.rs

@@ -1,2 +1,3 @@
+pub mod formats;
 pub mod input_handler;
 pub mod util;