[ty] IDE: only provide declarations and bindings as completions (#18456)

## Summary

Previously, all symbols where provided as possible completions. In an
example like the following, both `foo` and `f` were suggested as
completions, because `f` itself is a symbol.
```py
foo = 1

f<CURSOR>
```
Similarly, in the following example, `hidden_symbol` was suggested, even
though it is not statically visible:
```py
if 1 + 2 != 3:
    hidden_symbol = 1

hidden_<CURSOR>
```

With the change suggested here, we only use statically visible
declarations and bindings as a source for completions.


## Test Plan

- Updated snapshot tests
- New test for statically hidden definitions
- Added test for star import

crates/ty_python_semantic/src/semantic_model.rs

@@ -10,6 +10,7 @@ use crate::module_resolver::{Module, resolve_module};
 use crate::semantic_index::ast_ids::HasScopedExpressionId;
 use crate::semantic_index::semantic_index;
 use crate::semantic_index::symbol::FileScopeId;
+use crate::types::ide_support::all_declarations_and_bindings;
 use crate::types::{Type, binding_type, infer_scope_types};
 
 pub struct SemanticModel<'db> {
@@ -66,9 +67,10 @@ impl<'db> SemanticModel<'db> {
         };
         let mut symbols = vec![];
         for (file_scope, _) in index.ancestor_scopes(file_scope) {
-            for symbol in index.symbol_table(file_scope).symbols() {
-                symbols.push(symbol.name().clone());
-            }
+            symbols.extend(all_declarations_and_bindings(
+                self.db,
+                file_scope.to_scope_id(self.db, self.file),
+            ));
         }
         symbols
     }