Build libSwiftStaticMirror as a standalone library with minimal required dependencies.

This separates it from `libSwiftScan` and allows us to build this library without building much of the rest of the compiler.

Also refactor `utils/build-parser-lib` into `utils/build-tooling-libs` which builds both SwiftSyntaxParser and SwiftStaticMirror.

lib/DependencyScan/StringUtils.cpp

@@ -15,7 +15,7 @@
 #include <vector>
 
 namespace swift {
-namespace dependencies {
+namespace c_string_utils {
 
 swiftscan_string_ref_t create_null() {
   swiftscan_string_ref_t str;
@@ -64,5 +64,5 @@ swiftscan_string_set_t *create_empty_set() {
 const char *get_C_string(swiftscan_string_ref_t string) {
   return static_cast<const char *>(string.data);
 }
-} // namespace dependencies
+} // namespace c_string_utils
 } // namespace swift