…pache#17305)

* [BEAM-14267] Update watchForNewFiles to allow watching updated files

* Added overload versions of continuously for FileIO.match and .matchAll
  accepting a third matchUpdatedFiles parameter.

* Watching for both new files and timestamp change of existing files
  when matchUpdatedFiles is set as true

* run spotlessApply

* Fix Java Pre Commit

* Fix timing

* Update FileIO.populateDisplayData

* Address comments and add integration test

* Use a helper function for watch transfiorm

* Throw RuntimeException if extracting file timestamp fails

* Added GcsMatchIT testGcsMatchContinuously

* Move GcsMatchIT to correct path

* Add comment specifying the watch freq

* method naming; descriptive exception message

* Fix precommit checkstyleTest

* Fix test flacky in Dataflow

* Fix outdated comment

* Add dumb commit (a piece of comment for test) to trigger testing for PR