[syntax-errors] Detect single starred expression assignment x = *y (#17624)

## Summary

Part of #17412

Starred expressions cannot be used as values in assignment expressions.
Add a new semantic syntax error to catch such instances.
Note that we already have
`ParseErrorType::InvalidStarredExpressionUsage` to catch some starred
expression errors during parsing, but that does not cover top level
assignment expressions.

## Test Plan

- Added new inline tests for the new rule
- Found some examples marked as "valid" in existing tests (`_ = *data`),
which are not really valid (per this new rule) and updated them
- There was an existing inline test - `assign_stmt_invalid_value_expr`
which had instances of `*` expression which would be deemed invalid by
this new rule. Converted these to tuples, so that they do not trigger
this new rule.

crates/ruff_python_parser/resources/valid/statement/assignment.py

@@ -37,7 +37,7 @@ foo.bar = 42
 
 foo = 42
 
-[] = *data
-() = *data
+[] = (*data,)
+() = (*data,)
 a, b = ab
 a = b = c