move dataframe commands to nu-cmd-dataframe (#9241)

All of the dataframe commands ported over with no issues...

### 11 tests are commented out (for now)

So 100 of the original 111 tests are passing with only 11 tests being
ignored for now..

As per our conversation in the core team meeting on Wednesday
I took @jntrnr  suggestion and just commented out the tests dealing
with
[IntoDatetime](https://github.com/nushell/nushell/blob/main/crates/nu-command/src/conversions/into/mod.rs)

Later on we can move this functionality out of nu-command if we decide
it makes sense...

### The following tests were ignored...

```rust
modified:   crates/nu-cmd-dataframe/src/dataframe/series/date/get_day.rs
modified:   crates/nu-cmd-dataframe/src/dataframe/series/date/get_hour.rs
modified:   crates/nu-cmd-dataframe/src/dataframe/series/date/get_minute.rs

modified:   crates/nu-cmd-dataframe/src/dataframe/series/date/get_month.rs
modified:   crates/nu-cmd-dataframe/src/dataframe/series/date/get_nanosecond.rs
modified:   crates/nu-cmd-dataframe/src/dataframe/series/date/get_ordinal.rs

modified:   crates/nu-cmd-dataframe/src/dataframe/series/date/get_second.rs
modified:   crates/nu-cmd-dataframe/src/dataframe/series/date/get_week.rs
modified:   crates/nu-cmd-dataframe/src/dataframe/series/date/get_weekday.rs

modified:   crates/nu-cmd-dataframe/src/dataframe/series/date/get_year.rs
modified:   crates/nu-cmd-dataframe/src/dataframe/series/string/strftime.rs
```

crates/nu-command/src/lib.rs

@@ -61,12 +61,6 @@ pub use system::*;
 pub use util::*;
 pub use viewers::*;
 
-#[cfg(feature = "dataframe")]
-mod dataframe;
-
-#[cfg(feature = "dataframe")]
-pub use dataframe::*;
-
 #[cfg(feature = "sqlite")]
 mod database;