more closure serialization (#14698)

# Description

This PR introduces a switch `--serialize` that allows serializing of
types that cannot be deserialized. Right now it only serializes closures
as strings in `to toml`, `to json`, `to nuon`, `to text`, some indirect
`to html` and `to yaml`.

A lot of the changes are just weaving the engine_state through calling
functions and the rest is just repetitive way of getting the closure
block span and grabbing the span's text.

In places where it has to report `<Closure 123>` I changed it to
`closure_123`. It always seemed like the `<>` were not very nushell-y.
This is still a breaking change.

I think this could also help with systematic translation of old config
to new config file.


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crates/nu-command/tests/commands/database/into_sqlite.rs

@@ -1,6 +1,6 @@
 use chrono::{DateTime, FixedOffset};
 use nu_path::AbsolutePathBuf;
-use nu_protocol::{ast::PathMember, record, Span, Value};
+use nu_protocol::{ast::PathMember, engine::EngineState, record, Span, Value};
 use nu_test_support::{
     fs::{line_ending, Stub},
     nu, pipeline,
@@ -298,6 +298,9 @@ fn into_sqlite_existing_db_append() {
 /// streaming pipeline instead of a simple value
 #[test]
 fn into_sqlite_big_insert() {
+    let engine_state = EngineState::new();
+    // don't serialize closures
+    let serialize_types = false;
     Playground::setup("big_insert", |dirs, playground| {
         const NUM_ROWS: usize = 10_000;
         const NUON_FILE_NAME: &str = "data.nuon";
@@ -330,7 +333,14 @@ fn into_sqlite_big_insert() {
                 )
                 .unwrap();
 
-            let nuon = nuon::to_nuon(&value, nuon::ToStyle::Raw, Some(Span::unknown())).unwrap()
+            let nuon = nuon::to_nuon(
+                &engine_state,
+                &value,
+                nuon::ToStyle::Raw,
+                Some(Span::unknown()),
+                serialize_types,
+            )
+            .unwrap()
                 + &line_ending();
 
             nuon_file.write_all(nuon.as_bytes()).unwrap();