* Validate current node version (#19154)
* feat(12976): node version validation at runtime.
* refact(12976): move the code into a static utilities class.
* test(12976): added first test case using jest.
* test(12976): added test cases for node_version.
* feat(12976): create setup env node to bootstrap babel, ts-node and node version validator.
* refact(12976): migrated node version code from es6 to es5.
* feat(12976): node version validation at runtime.
* refact(12976): move the code into a static utilities class.
* test(12976): added first test case using jest.
* test(12976): added test cases for node_version.
* feat(12976): create setup env node to bootstrap babel, ts-node and node version validator.
* refact(12976): migrated node version code from es6 to es5.
* fix(12976): remove one level from ts node register cache directory link.
* chore(12976): added caret to semver dependecy in order to support minor versions.
* refact(12976): small change from named import to default import on node version validator.
* refact(12976): removed ts_node_register and add the code to babel_register.
* feat(12976): split eslint config in order to properly support files built to run before and after node version validator. refact(12976): convert script files to es5 code. refact(12976): delete inline eslint configs from node version check related files.
* refact(12976): remove ts node register file.
* refact(12976): completely port setup_node_env to es5.
* refact(12976): remove babel_register invokation from external dependencies in scripts.
* refact(12976): move node_version code directly into node_version_validator inside setup_node_env folder.
* refact(12976): only node version validator for kbn script.
* Fix check_file_casing babel_register reference (#19457)
* chore(12976): fixed license headers on new files.
* Introduce `kbn`, the Kibana build tool
* yarn kbn
* Make all deps devDeps
* Exclude __fixtures__ folder from Jest to avoid warnings
* Review fixes
* Update readme
* Use 'yarn kbn'
* Consistent rootPath
* Link to kbn tool
* Unsupported URL 'debug help' in contributing guide
