synchronize ECJ linter with eclipse IDE [LUCENE-9881]

[asfimport]

Currently the IDE configuration is different from the linter.

Some checks in the eclipse linter are currently disabled, but will show in the IDE and vice-versa.

In the eclipse IDE, the experience is terrible: there are hundreds of useless warnings that won't actually fail lucene's build. It also enforces some things as error that make experimentation frustrating (such as unused imports)

I think we should remove the duplication. linter config should have all of the compiler config. And we should just combine linter config, converting all errors into warnings, with the formatting settings into one file during gradle eclipse

This way, if you see an eclipse warning, you know it will fail the lucene build. But you are no longer forced to fix unused imports to quickly try something out and run a unit test in the IDE, for example.

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Migrated from LUCENE-9881 by Robert Muir (@rmuir), updated Mar 27 2021 Pull requests: https://github.com/apache/lucene/pull/46

[asfimport]

ASF subversion and git services (migrated from JIRA)

Commit 690e256ec9f633dd06e34d87a437fa22c997019c in lucene's branch refs/heads/main from Robert Muir https://gitbox.apache.org/repos/asf?p=lucene.git;h=690e256

LUCENE-9881: synchronize ECJ linter with Eclipse IDE (#46)

Co-authored-by: Uwe Schindler <uschindler@apache.org>

[asfimport]

ASF subversion and git services (migrated from JIRA)

Commit 3538709269fedfc349f06d8486bee71540329fbb in lucene's branch refs/heads/main from Uwe Schindler https://gitbox.apache.org/repos/asf?p=lucene.git;h=3538709

Improvement for LUCENE-9881 (#46): Completely disable Eclipse plugins's eclipseJdt task and replace by owur own just copying the filtered config files. This now works correctly with inputs/outputs.