added header recipe

[Anmol202005]

Fixes: #25

Added header recipe: Adds headers to Java source files when missing.

[romani]

Please put reference to issue to commit message .
Please always do it.

[Anmol202005]

@rdiachenko kindly review.

[rdiachenko]

@Anmol202005 its a lot of issues here becuase you mixed different logic. Please split this PR into the following:

1. PR for header recipe implementation only, no integration with config and parent recipe
2. PR for loading checkstyle config given config file uri
3. PR for using header recipe with config

Please prioritise smaller PRs with independet changes rather than putting everything into one PR to minimise review time and iteration

[Anmol202005]

@rdiachenko
Done.
This PR now deals with header recipe implementation only.

[rdiachenko]

@Anmol202005 the check has fileExtensions and in this recipe we only fix java files. We can't fix all files that OpenRewrite can't parse, could you check this? If yes, we should mark this recipe as "partially covered" in the readme

[Anmol202005]

@rdiachenko kindly review :)

[rdiachenko]

I think we should replace these Checkstyle specific objects with our own like we did with CheckstyleViolation. This will help to avoid Checkstyle dependencies to be spread all around the recipes and have control over needed fields. To not overcomplicate this PR, I'm ok to fix it as part of the PR, which introduces configuration. @Anmol202005 please make a note in the issue to address this point

[Anmol202005]

done. updated issue: #36

[Anmol202005]

@rdiachenko done.

[Anmol202005]

@rdiachenko done.

[Anmol202005]

@rdiachenko Done.

[timurt]

LGTM @Anmol202005 thanks for your work!

[rdiachenko]

This PR is not ideal but already took a lot of time and effort.

Ok to merge after this comment got responed #35 (comment)