Allow fixing directory structure not matching package paths

Following the recent addition of the `directory-package-mismatch` rule,
this PR brings a corresponding `regal fix` remediator as well as a code
action to fix this directly in the editor.

Fixes StyraInc#1025

Signed-off-by: Anders Eknert <anders@styra.com>

pkg/fixer/fixes/directorypackagemismatch.go

@@ -46,6 +46,11 @@ func (d *DirectoryPackageMismatch) Fix(fc *FixCandidate, opts *RuntimeOptions) (
 
 	rootPath = filepath.Clean(rootPath)
 
+	// We must ensure that any file provided resides under the root path!
+	if _, err = filepath.Rel(rootPath, fc.Filename); err != nil {
+		return nil, fmt.Errorf("path not relative to root path: %w", err)
+	}
+
 	newPath := filepath.Join(rootPath, pkgPath, filepath.Base(fc.Filename))
 
 	if newPath == fc.Filename {

pkg/fixer/fixes/fixes.go

@@ -52,6 +52,7 @@ type Fix interface {
 type RuntimeOptions struct {
 	// BaseDir is the base directory for the files being fixed. This is often the same as the
 	// workspace root directory, but not necessarily.
+	// TODO: use a slice and allow more than one?
 	BaseDir   string
 	Config    *config.Config
 	Client    clients.Identifier

tmp/unrelated.txt

@@ -0,0 +1 @@
+foo