RFR: 8223373: Remove IntelliJ IDEA specific files from the source code repository [v6]

[Ambarish Rapte]

On Sat, 15 Apr 2023 23:32:40 GMT, Thiago Milczarek Sayao <tsayao at openjdk.org> wrote:

>> This PR does:
>> 
>> - Remove specific Idea files and let it be imported from gradle;
>> - Adds checkstyle (to use with checkstyle plugin - it will let you know style mistakes);
>> - Configures auto-format to sun style (with the changes mentioned in [Code Style Rules](https://wiki.openjdk.org/display/OpenJFX/Code+Style+Rules));
>> - Automatically sets Copyright notice (updates year too);
>
> Thiago Milczarek Sayao has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Update .gitignore
>  - Remove unrelated gitignore

Looks good.
Did not face any problem when loading the project in idea, changing properties, editing files.

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Marked as reviewed by arapte (Reviewer).

PR Review: https://git.openjdk.org/jfx/pull/1009#pullrequestreview-1452286626