[LIC] Simplified licence header across the project

[ashwin-pc]

Signed-off-by: Ashwin Pc [email protected]

Description

Updates the license header across the project to reflect the simpler and more accurate license header (Issue: opensearch-project/.github#21)

The 4 changes here are:

1. ESLint rule to enforce only the smaller header
2. Split and update existing headers across the project so that the new header and the existing ones are maintained
3. Adds src/legacy/core_plugins/opensearch-dashboards/public/context/query_parameters to pre-commit hook's file glob ignore pattern and removes the unused src/legacy/ui/public/flot-charts pattern. (link
4. Updates schema_error.test.ts.snap due to the header change (line number for the error changes due to the location of the error)

Aside from changes 1,3 and 4, every other file should only have a header change.

Issues Resolved

• Correct copyright notices to reflect Copyright OpenSearch Contributors .github#21

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed per the DCO using --signoff

[mihirsoni]

Assuming entire change is just a lic header change.

[tmarkley]

I don't think changes to all files is required. Based on what dB said in opensearch-project/.github#21, we only need to add the # Copyright OpenSearch Contributors line to files that are new (and not from the forked project). I think we may have missed some of the new files from #826, but otherwise we shouldn't be modifying every file in the repo.

[ashwin-pc]

@tmarkley looks like you are right. The copy i was referring to was updated yesterday making most of this PR unnecessary. This also makes the change needed far smaller and readable. Will close this PR and open a new one so that git does not freak out over so many files being reverted.