Add support for specifying minimum dots in detected string imports (#19538)

## Summary

Defaults to requiring two dots, which matches the Pants default.

crates/ruff_workspace/src/options.rs

@@ -3843,6 +3843,12 @@ pub struct AnalyzeOptions {
         "#
     )]
     pub detect_string_imports: Option<bool>,
+    /// The minimum number of dots in a string to consider it a valid import.
+    ///
+    /// This setting is only relevant when [`detect-string-imports`](#detect-string-imports) is enabled.
+    /// For example, if this is set to `2`, then only strings with at least two dots (e.g., `"path.to.module"`)
+    /// would be considered valid imports.
+    pub string_imports_min_dots: Option<usize>,
     /// A map from file path to the list of Python or non-Python file paths or globs that should be
     /// considered dependencies of that file, regardless of whether relevant imports are detected.
     #[option(