Create Record type (#10103)

# Description
This PR creates a new `Record` type to reduce duplicate code and
possibly bugs as well. (This is an edited version of #9648.)
- `Record` implements `FromIterator` and `IntoIterator` and so can be
iterated over or collected into. For example, this helps with
conversions to and from (hash)maps. (Also, no more
`cols.iter().zip(vals)`!)
- `Record` has a `push(col, val)` function to help insure that the
number of columns is equal to the number of values. I caught a few
potential bugs thanks to this (e.g. in the `ls` command).
- Finally, this PR also adds a `record!` macro that helps simplify
record creation. It is used like so:
   ```rust
   record! {
       "key1" => some_value,
       "key2" => Value::string("text", span),
       "key3" => Value::int(optional_int.unwrap_or(0), span),
       "key4" => Value::bool(config.setting, span),
   }
   ```
Since macros hinder formatting, etc., the right hand side values should
be relatively short and sweet like the examples above.

Where possible, prefer `record!` or `.collect()` on an iterator instead
of multiple `Record::push`s, since the first two automatically set the
record capacity and do less work overall.

# User-Facing Changes
Besides the changes in `nu-protocol` the only other breaking changes are
to `nu-table::{ExpandedTable::build_map, JustTable::kv_table}`.

crates/nu-protocol/src/module.rs

@@ -136,16 +136,14 @@ impl Module {
                 }
             }
 
-            let mut const_cols = vec![];
-            let mut const_vals = vec![];
-
-            for (name, val) in const_rows {
-                const_cols.push(String::from_utf8_lossy(&name).to_string());
-                const_vals.push(val);
-            }
-
             let span = self.span.unwrap_or(backup_span);
-            let const_record = Value::record(const_cols, const_vals, span);
+            let const_record = Value::record(
+                const_rows
+                    .into_iter()
+                    .map(|(name, val)| (String::from_utf8_lossy(&name).to_string(), val))
+                    .collect(),
+                span,
+            );
 
             return (
                 ResolvedImportPattern::new(