Rename misused "deprecation" to removal (#10000)

# Description
In the past we named the process of completely removing a command and
providing a basic error message pointing to the new alternative
"deprecation".

But this doesn't match the expectation of most users that have seen
deprecation _warnings_ that alert to either impending removal or
discouraged use after a stability promise.

# User-Facing Changes
Command category changed from `deprecated` to `removed`

crates/nu-protocol/src/engine/engine_state.rs

@@ -713,7 +713,7 @@ impl EngineState {
             for decl in &overlay_frame.decls {
                 if overlay_frame.visibility.is_decl_id_visible(decl.1) && predicate(decl.0) {
                     let command = self.get_decl(*decl.1);
-                    if ignore_deprecated && command.signature().category == Category::Deprecated {
+                    if ignore_deprecated && command.signature().category == Category::Removed {
                         continue;
                     }
                     output.push((decl.0.clone(), Some(command.usage().to_string())));
@@ -1713,8 +1713,7 @@ impl<'a> StateWorkingSet<'a> {
                 for decl in &overlay_frame.decls {
                     if overlay_frame.visibility.is_decl_id_visible(decl.1) && predicate(decl.0) {
                         let command = self.get_decl(*decl.1);
-                        if ignore_deprecated && command.signature().category == Category::Deprecated
-                        {
+                        if ignore_deprecated && command.signature().category == Category::Removed {
                             continue;
                         }
                         output.push((decl.0.clone(), Some(command.usage().to_string())));

crates/nu-protocol/src/shell_error.rs

@@ -982,30 +982,17 @@ pub enum ShellError {
     #[diagnostic()]
     OutsideSpannedLabeledError(#[source_code] String, String, String, #[label("{2}")] Span),
 
-    /// Attempted to use a deprecated command.
+    /// Attempted to use a command that has been removed from Nushell.
     ///
     /// ## Resolution
     ///
     /// Check the help for the new suggested command and update your script accordingly.
-    #[error("Deprecated command {0}")]
-    #[diagnostic(code(nu::shell::deprecated_command))]
-    DeprecatedCommand(
+    #[error("Removed command: {0}")]
+    #[diagnostic(code(nu::shell::removed_command))]
+    RemovedCommand(
         String,
         String,
-        #[label = "'{0}' is deprecated. Please use '{1}' instead."] Span,
-    ),
-
-    /// Attempted to use a deprecated parameter.
-    ///
-    /// ## Resolution
-    ///
-    /// Check the help for the command and update your script accordingly.
-    #[error("Deprecated parameter {0}")]
-    #[diagnostic(code(nu::shell::deprecated_command))]
-    DeprecatedParameter(
-        String,
-        String,
-        #[label = "Parameter '{0}' is deprecated. Please use '{1}' instead."] Span,
+        #[label = "'{0}' has been removed from Nushell. Please use '{1}' instead."] Span,
     ),
 
     /// Non-Unicode input received.

crates/nu-protocol/src/signature.rs

@@ -49,7 +49,7 @@ pub enum Category {
     Date,
     Debug,
     Default,
-    Deprecated,
+    Removed,
     Env,
     Experimental,
     FileSystem,
@@ -81,7 +81,7 @@ impl std::fmt::Display for Category {
             Category::Date => "date",
             Category::Debug => "debug",
             Category::Default => "default",
-            Category::Deprecated => "deprecated",
+            Category::Removed => "removed",
             Category::Env => "env",
             Category::Experimental => "experimental",
             Category::FileSystem => "filesystem",