Finish removing CLR local-string dependencies

[simonrozsival]

Summary

• calculate the complete directory path size before copying it
• use the existing sensible local buffer for common paths and malloc() only for larger values
• temporarily terminate each path component in place before passing it to mkdir()
• preserve paths larger than the former inline-storage threshold
• preserve filesystem errno across conditional heap cleanup
• remove the final CLR/NativeAOT strings.hh includes after the lower stack layers migrate their consumers

This is the top PR in stack #12519. Together, the stack removes all CLR/NativeAOT uses of the local-string hierarchy and their strings.hh dependencies.

Validation

• Local native builds intentionally skipped; relying on CI validation

[Copilot]

Pull request overview

Updates the CLR runtime Util::create_directory() helper to avoid dynamic local-string allocation by using a fixed-size stack buffer and in-place component termination when creating intermediate directories.

Changes:

• Replaces dynamic_local_string<Constants::SENSIBLE_PATH_MAX> usage with a fixed char buffer sized to Constants::SENSIBLE_PATH_MAX.
• Adds an explicit length check and returns ENAMETOOLONG when the input path does not fit.
• Temporarily NUL-terminates each path component in-place before calling mkdir().

Show a summary per file

File	Description
src/native/clr/runtime-base/util.cc	Switch create_directory() to a fixed stack buffer, add bounded-length rejection, and use in-place component termination before mkdir().

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 1
• Review effort level: Lite