(bug) - Add synchronization to Dir.chdir in init_puppet_lint

This commit wraps the `Dir.chdir` call in the `validation_provider.rb`
file within a `$PuppetParserMutex.synchronize` block.

Before this change, the `Dir.chdir` method was called without synchronization,
which could lead to conflicts if another `chdir` block was in progress.

This change prevents the error "(puppet/fixDiagnosticErrors) conflicting chdir
during another chdir block" by ensuring that the `Dir.chdir` call is only
executed by one thread at a time.

Author: jordanbreen28

lib/puppet-languageserver/manifest/validation_provider.rb

@@ -109,7 +109,9 @@ def self.init_puppet_lint(root_dir, lint_options = [])
           linter_options = PuppetLint::OptParser.build
         else
           begin
-            Dir.chdir(root_dir.to_s) { linter_options = PuppetLint::OptParser.build }
+            $PuppetParserMutex.synchronize do # rubocop:disable Style/GlobalVars
+              Dir.chdir(root_dir.to_s) { linter_options = PuppetLint::OptParser.build }
+            end
           rescue OptionParser::InvalidOption => e
             PuppetLanguageServer.log_message(:error, "(#{name}) Error reading Puppet Lint configuration.  Using default: #{e}")
             linter_options = PuppetLint::OptParser.build