RFR: JDK-8223373: Remove IntelliJ IDEA specific files from the source code repository [v4]

[Thiago Milczarek Sayao]

> 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);
> - Run configurations for samples/toys and builds.

Thiago Milczarek Sayao has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 50 additional commits since the last revision:

 - Do not change gradle files
   MissingJavadocMethod is too annoying
 - Merge branch 'master' into jfx_intellij_idea
 - Merge branch 'openjdk:master' into master
 - Merge branch 'openjdk:master' into master
 - Merge branch 'openjdk:master' into master
 - Use java 17 by default
 - Review changes
 - Allow 20 parameters and _methods()
 - Add UI folder
 - Add manual tests
 - ... and 40 more: https://git.openjdk.org/jfx/compare/4d9d2fda...896552a9

-------------

Changes:
  - all: https://git.openjdk.org/jfx/pull/1009/files
  - new: https://git.openjdk.org/jfx/pull/1009/files/56b256cc..896552a9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1009&range=03
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1009&range=02-03

  Stats: 198289 lines in 5614 files changed: 117261 ins; 42908 del; 38120 mod
  Patch: https://git.openjdk.org/jfx/pull/1009.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/1009/head:pull/1009

PR: https://git.openjdk.org/jfx/pull/1009