Add ASF header and RAT CI

[aglinxinyuan]

Add the ASF header to all source code in the repo and introduce RAT CI.

Apache Release Audit Tool (RAT) is a release audit tool focused on licenses.

This PR adds the release audit tool to the GitHub Action workflow (CI).

This would allow developers to quickly detect if new files during a PR submission or commit push were missing the license header.

Add files to the optional .ratignore file if you want to exclude certain files and folders from being tested.

[pjfanning]

@chenlica @aglinxinyuan @shengquan-ni @bobbai00 @parshimers this should possibly be reverted. It removed 3rd party licenses from source files.
This is not allowed. You must keep the pre-existing license headers and not add Apache license headers to those files.
All the files that have pre-existing license headers must be mentioned in the Texera LICENSE file.

https://github.com/apache/pekko/blob/main/LICENSE is an example of a LICENSE that lists the 3rd party files in Pekko.

If we have any 3rd party code from Apache licensed projects, then we may also need to add a mention of the related NOTICE terms in the Texera NOTICE file.

[aglinxinyuan]

Sure. We can add the third party headers back and add them to the LICENSE file.

[chenlica]

Thank you, @pjfanning and @aglinxinyuan .

[aglinxinyuan]

All 1,444 files were manually checked, and only the following three files had their headers mistakenly removed in this PR:

1. core/pyright-language-server/src/language-server-runner.ts
2. core/pyright-language-server/src/main.ts
3. core/pyright-language-server/src/server-commons.ts

I will restore the headers in PR #4132.