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

[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.

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Commit messages:
 - Allow 20 parameters and _methods()
 - Add UI folder
 - Add manual tests
 - Remove Compile_with_MEDIA___WEBKIT.xml
 - Add hs_err*.log, .DS_Store to .gitignore
 - Add Run configuration to build MEDIA and WEBKIT
 - Checkstyle: Allow parameters with same name as fields
 - Add run configuration for robot tests
 - Be more realistic on checking javadoc
 - checkstyle.xml: allow 120 chars line
 - ... and 33 more: https://git.openjdk.org/jfx/compare/294e82e6...31e59b26

Changes: https://git.openjdk.org/jfx/pull/1009/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1009&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8223373
  Stats: 966 lines in 42 files changed: 448 ins; 511 del; 7 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