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/env/load_env.rs

@@ -2,7 +2,7 @@ use nu_engine::{current_dir, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Type, Value,
+    Category, Example, PipelineData, Record, ShellError, Signature, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -39,12 +39,12 @@ impl Command for LoadEnv {
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        let arg: Option<(Vec<String>, Vec<Value>)> = call.opt(engine_state, stack, 0)?;
+        let arg: Option<Record> = call.opt(engine_state, stack, 0)?;
         let span = call.head;
 
         match arg {
-            Some((cols, vals)) => {
-                for (env_var, rhs) in cols.into_iter().zip(vals) {
+            Some(record) => {
+                for (env_var, rhs) in record {
                     let env_var_ = env_var.as_str();
                     if ["FILE_PWD", "CURRENT_FILE", "PWD"].contains(&env_var_) {
                         return Err(ShellError::AutomaticEnvVarSetManually {
@@ -57,8 +57,8 @@ impl Command for LoadEnv {
                 Ok(PipelineData::empty())
             }
             None => match input {
-                PipelineData::Value(Value::Record { cols, vals, .. }, ..) => {
-                    for (env_var, rhs) in cols.into_iter().zip(vals) {
+                PipelineData::Value(Value::Record { val, .. }, ..) => {
+                    for (env_var, rhs) in val {
                         let env_var_ = env_var.as_str();
                         if ["FILE_PWD", "CURRENT_FILE"].contains(&env_var_) {
                             return Err(ShellError::AutomaticEnvVarSetManually {

crates/nu-command/src/env/with_env.rs

@@ -94,8 +94,8 @@ fn with_env(
             if table.len() == 1 {
                 // single row([[X W]; [Y Z]])
                 match &table[0] {
-                    Value::Record { cols, vals, .. } => {
-                        for (k, v) in cols.iter().zip(vals.iter()) {
+                    Value::Record { val, .. } => {
+                        for (k, v) in val {
                             env.insert(k.to_string(), v.clone());
                         }
                     }
@@ -122,8 +122,8 @@ fn with_env(
             }
         }
         // when get object by `open x.json` or `from json`
-        Value::Record { cols, vals, .. } => {
-            for (k, v) in cols.iter().zip(vals) {
+        Value::Record { val, .. } => {
+            for (k, v) in val {
                 env.insert(k.clone(), v.clone());
             }
         }