Fix a bug where auto-fixed code could not be retrieved via GetFile API

[wata727]

Fixes #1958

Autofix saves the fixed file in memory and writes them to the file system at the end. Therefore, if each rule always loads files from the file system, there is a problem that autofix that have been applied halfway cannot be properly reflected. To prevent this, TFLint's plugin server has the GetFile API that returns files based on auto-fixed code.

tflint/plugin/server.go

Lines 73 to 81 in cc6168c

	// GetFile returns the hcl.File based on passed the file name.
	func (s *GRPCServer) GetFile(name string) (*hcl.File, error) {
	// Considering that autofix has been applied, prioritize returning the value of runner.Files().
	if file, exists := s.runner.Files()[name]; exists {
	return file, nil
	}
	// If the file is not found in the current module, it may be in other modules (e.g. root module).
	return s.files[name], nil
	}

The auto-fixed code is applied in the runner by runner.ApplyChanges, so it can be retrieved in runner.Files.

However, there was a bug in runner.Files that prevented it from returning properly fixed files. As a result, it fell back to GRPCServer.files and returned the code before the fix, which caused HCL parsing errors due to unintended range parsing.

The details of the bug are incorrect filtering based on module directory. The runner.Files returns only the files that make up a Terraform module that match the module's source directory.

tflint/tflint/runner.go

Lines 214 to 223 in cc6168c

	// Files returns the raw *hcl.File representation of all Terraform configuration in the module directory.
	func (r *Runner) Files() map[string]*hcl.File {
	result := make(map[string]*hcl.File)
	for name, file := range r.TFConfig.Module.Files {
	if filepath.Dir(name) == filepath.Clean(r.TFConfig.Module.SourceDir) {
	result[name] = file
	}
	}
	return result
	}

In this case, the SourceDir will match in most cases, but if --chdir or --recursive is used, the SourceDir will be a relative path from the changed directory, while the Files path will be relative from the original directory. For example, when executed with --chdir=subdir, the SourceDir will be "./" and the File path will be "subdir/main.tf".

To fix this bug, I completely removed filtering by module directory. Originally, this was introduced to avoid returning all files parsed by the HCL parser #762. However, in #1428, runner.files was replaced with the Terraform module files instead of the parser sources, so this filtering is no longer effective.
https://github.com/terraform-linters/tflint/pull/1428/files#diff-1949a8b20814ca4596fa340c7409af6fb657da070446c633b42cfa095a10d2d9L447-R350