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-command/src/strings/str_/trim/trim_.rs

@@ -1,10 +1,10 @@
 use nu_cmd_base::input_handler::{operate, CmdArgument};
 use nu_engine::CallExt;
-use nu_protocol::Category;
 use nu_protocol::{
     ast::{Call, CellPath},
     engine::{Command, EngineState, Stack},
-    Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
+    Category, Example, PipelineData, Record, ShellError, Signature, Span, Spanned, SyntaxShape,
+    Type, Value,
 };
 
 #[derive(Clone)]
@@ -180,14 +180,16 @@ fn action(input: &Value, arg: &Arguments, head: Span) -> Value {
         Value::Error { .. } => input.clone(),
         other => match mode {
             ActionMode::Global => match other {
-                Value::Record { cols, vals, span } => {
-                    let new_vals = vals.iter().map(|v| action(v, arg, head)).collect();
+                Value::Record { val: record, span } => {
+                    let new_vals = record.vals.iter().map(|v| action(v, arg, head)).collect();
 
-                    Value::Record {
-                        cols: cols.to_vec(),
-                        vals: new_vals,
-                        span: *span,
-                    }
+                    Value::record(
+                        Record {
+                            cols: record.cols.to_vec(),
+                            vals: new_vals,
+                        },
+                        *span,
+                    )
                 }
                 Value::List { vals, span } => {
                     let new_vals = vals.iter().map(|v| action(v, arg, head)).collect();
@@ -249,14 +251,12 @@ mod tests {
     }
 
     fn make_record(cols: Vec<&str>, vals: Vec<&str>) -> Value {
-        Value::Record {
-            cols: cols.iter().map(|x| x.to_string()).collect(),
-            vals: vals
-                .iter()
-                .map(|x| Value::test_string(x.to_string()))
+        Value::test_record(
+            cols.into_iter()
+                .zip(vals)
+                .map(|(col, val)| (col.to_owned(), Value::test_string(val)))
                 .collect(),
-            span: Span::test_data(),
-        }
+        )
     }
 
     fn make_list(vals: Vec<&str>) -> Value {