Name the Value conversion functions more clearly (#11851)

# Description
This PR renames the conversion functions on `Value` to be more consistent.
It follows the Rust [API guidelines](https://rust-lang.github.io/api-guidelines/naming.html#ad-hoc-conversions-follow-as_-to_-into_-conventions-c-conv) for ad-hoc conversions.
The conversion functions on `Value` now come in a few forms:
- `coerce_{type}` takes a `&Value` and attempts to convert the value to
`type` (e.g., `i64` are converted to `f64`). This is the old behavior of
some of the `as_{type}` functions -- these functions have simply been
renamed to better reflect what they do.
- The new `as_{type}` functions take a `&Value` and returns an `Ok`
result only if the value is of `type` (no conversion is attempted). The
returned value will be borrowed if `type` is non-`Copy`, otherwise an
owned value is returned.
- `into_{type}` exists for non-`Copy` types, but otherwise does not
attempt conversion just like `as_type`. It takes an owned `Value` and
always returns an owned result.
- `coerce_into_{type}` has the same relationship with `coerce_{type}` as
`into_{type}` does with `as_{type}`.
- `to_{kind}_string`: conversion to different string formats (debug,
abbreviated, etc.). Only two of the old string conversion functions were
removed, the rest have been renamed only.
- `to_{type}`: other conversion functions. Currently, only `to_path`
exists. (And `to_string` through `Display`.)

This table summaries the above:
| Form | Cost | Input Ownership | Output Ownership | Converts `Value`
case/`type` |
| ---------------------------- | ----- | --------------- |
---------------- | -------- |
| `as_{type}` | Cheap | Borrowed | Borrowed/Owned | No |
| `into_{type}` | Cheap | Owned | Owned | No |
| `coerce_{type}` | Cheap | Borrowed | Borrowed/Owned | Yes |
| `coerce_into_{type}` | Cheap | Owned | Owned | Yes |
| `to_{kind}_string` | Expensive | Borrowed | Owned | Yes |
| `to_{type}` | Expensive | Borrowed | Owned | Yes |

# User-Facing Changes
Breaking API change for `Value` in `nu-protocol` which is exposed as
part of the plugin API.

crates/nu-command/src/platform/ansi/ansi_.rs

@@ -738,7 +738,7 @@ fn heavy_lifting(code: Value, escape: bool, osc: bool, call: &Call) -> Result<St
         });
     }
     let code_string = if param_is_string {
-        code.as_string().expect("error getting code as string")
+        code.coerce_string().expect("error getting code as string")
     } else {
         "".to_string()
     };
@@ -798,9 +798,10 @@ fn heavy_lifting(code: Value, escape: bool, osc: bool, call: &Call) -> Result<St
             }
         }
     } else {
+        let span = code.span();
         // This is a record that should look like
         // { fg: "#ff0000" bg: "#00ff00" attr: bli }
-        let record = code.as_record()?;
+        let record = code.into_record()?;
         // create a NuStyle to parse the information into
         let mut nu_style = nu_color_config::NuStyle {
             fg: None,
@@ -810,13 +811,13 @@ fn heavy_lifting(code: Value, escape: bool, osc: bool, call: &Call) -> Result<St
         // Iterate and populate NuStyle with real values
         for (k, v) in record {
             match k.as_str() {
-                "fg" => nu_style.fg = Some(v.as_string()?),
-                "bg" => nu_style.bg = Some(v.as_string()?),
-                "attr" => nu_style.attr = Some(v.as_string()?),
+                "fg" => nu_style.fg = Some(v.coerce_into_string()?),
+                "bg" => nu_style.bg = Some(v.coerce_into_string()?),
+                "attr" => nu_style.attr = Some(v.coerce_into_string()?),
                 _ => {
                     return Err(ShellError::IncompatibleParametersSingle {
                         msg: format!("unknown ANSI format key: expected one of ['fg', 'bg', 'attr'], found '{k}'"),
-                        span: code.span(),
+                        span,
                     })
                 }
             }

crates/nu-command/src/platform/ansi/strip.rs

@@ -81,7 +81,7 @@ fn action(input: &Value, args: &Arguments, _span: Span) -> Value {
         other => {
             // Fake stripping ansi for other types and just show the abbreviated string
             // instead of showing an error message
-            Value::string(other.into_abbreviated_string(&args.config), span)
+            Value::string(other.to_abbreviated_string(&args.config), span)
         }
     }
 }

crates/nu-command/src/platform/input/list.rs

@@ -95,9 +95,9 @@ impl Command for InputList {
                     let display_value = if let Some(ref cellpath) = display_path {
                         val.clone()
                             .follow_cell_path(&cellpath.members, false)?
-                            .into_string(", ", engine_state.get_config())
+                            .to_expanded_string(", ", engine_state.get_config())
                     } else {
-                        val.into_string(", ", engine_state.get_config())
+                        val.to_expanded_string(", ", engine_state.get_config())
                     };
                     Ok(Options {
                         name: display_value,