Print directory change notifications around tool execution

Summary

    Print Entering directory '...' and Leaving directory '...' around tool invocations in _run_tool()
    Enables editors (Emacs, etc.) to resolve file paths in tool output when running from a build directory

Motivation

When edalize runs a tool (e.g. slang for linting), it sets cwd=self.work_root, so the tool reports file paths relative to the build directory. Editors that parse compiler output (like Emacs compilation-mode) cannot resolve these paths back to the source files.

GNU Make solved this with Entering directory / Leaving directory messages. This patch adds the same convention to edalize so that editor integrations work out of the box.
Test plan

    Run any edalize-backed tool (e.g. fusesoc run --target=slanglint ...)
    Verify Entering directory and Leaving directory appear in output
    Verify editor can resolve relative file paths in tool output to correct source locations

Author: per-rtl

edalize/edatool.py

@@ -568,6 +568,8 @@ def _run_tool(self, cmd, args=[], quiet=False):
         logger.debug("args  : " + " ".join(args))
 
         capture_output = quiet and not (self.verbose or self.stdout or self.stderr)
+        abs_work_root = os.path.abspath(self.work_root)
+        print(f"Entering directory '{abs_work_root}'")
         try:
             cp = run(
                 [cmd] + args,
@@ -593,6 +595,7 @@ def _run_tool(self, cmd, args=[], quiet=False):
                 logger.debug(e.stderr)
 
             raise RuntimeError(_s)
+        print(f"Leaving directory '{abs_work_root}'")
         return cp.returncode, cp.stdout, cp.stderr
 
     def _filter_verilog_files(src_file):