[red-knot] Resolve Options to Settings (#16000)

## Summary

This PR generalize the idea that we may want to emit diagnostics for 
invalid or incompatible configuration values similar to how we already 
do it for `rules`. 

This PR introduces a new `Settings` struct that is similar to `Options`
but, unlike
`Options`, are fields have their default values filled in and they use a
representation optimized for reads.

The diagnostics created during loading the `Settings` are stored on the
`Project` so that we can emit them when calling `check`.

The motivation for this work is that it simplifies adding new settings.
That's also why I went ahead and added the `terminal.error-on-warning`
setting to demonstrate how new settings are added.

## Test Plan

Existing tests, new CLI test.

crates/red_knot_python_semantic/src/db.rs

@@ -1,3 +1,5 @@
+use std::sync::Arc;
+
 use crate::lint::{LintRegistry, RuleSelection};
 use ruff_db::files::File;
 use ruff_db::{Db as SourceDb, Upcast};
@@ -7,7 +9,7 @@ use ruff_db::{Db as SourceDb, Upcast};
 pub trait Db: SourceDb + Upcast<dyn SourceDb> {
     fn is_file_open(&self, file: File) -> bool;
 
-    fn rule_selection(&self) -> &RuleSelection;
+    fn rule_selection(&self) -> Arc<RuleSelection>;
 
     fn lint_registry(&self) -> &LintRegistry;
 }
@@ -111,8 +113,8 @@ pub(crate) mod tests {
             !file.path(self).is_vendored_path()
         }
 
-        fn rule_selection(&self) -> &RuleSelection {
-            &self.rule_selection
+        fn rule_selection(&self) -> Arc<RuleSelection> {
+            self.rule_selection.clone()
         }
 
         fn lint_registry(&self) -> &LintRegistry {