cleaning hidden and ignored files

[roberto-butti]

Pull request type

Jira Link: not internal

• [ ] Bugfix
• [ ] Feature
• [x] Code style update (formatting, renaming)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Other (please describe):

How to test this PR

.DS_Store (MacOSX hidden file), and .idea folder (specific for some editors) are not committed in the repository. This PR aim to avoid pushing these "local" files in the repo.

What is the new behavior?

• .DS_Store is removed on the repo
• .DS_Store and .idea are listed as git ignored files

Other information

Files removed:

./.DS_Store
./tests/.DS_Store
./tests/Data/.DS_Store

[joaokamun]

Thanks!