Elasticsearch Windows MSI package

## Summary
This is an experimental status issue, documenting known remaining tasks before Elasticsearch is ready to move to GA as part of [Elastic Stack Installers](https://github.com/elastic/elastic-stack-installers). This repository contains MSI package build framework (ElastiBuild) capable of discovering various artifacts from local file system and artifacts API, fetching, unpacking and building supported MSI packages.

- Support building and testing Elasticsearch MSI within ElastiBuild framework.

Below we outline a high level plan of changes that will help us achieve the above goals:
- [ ] Internal refactoring of ElastiBuild Package Compiler projects
- [ ] Support for parsing, fetching and unpacking Elasticsearch-specific artifact names (vs Beats and Kibana)
- [ ] Evaluate options and decide on implementation for running Elasticsearch as Windows Service
- [ ] Implement running Elasticsearch as Windows Service and appropriate installer support

Note to self: https://github.com/elastic/elasticsearch-net-abstractions

## Relevant User Requests, Issues and Potential Improvements:
- [ ] MSI package doesn't upgrade log4j2.properties file
https://github.com/elastic/windows-installers/issues/351
- [ ] Specify License file
https://github.com/elastic/windows-installers/issues/277
https://github.com/elastic/windows-installers/issues/126
- [ ] The uninstaller won't work if heap size is changed in settings to more than 1/2 manually
https://github.com/elastic/windows-installers/issues/244
- [ ] Configure ML node role
https://github.com/elastic/windows-installers/issues/194
- [ ] Computing Space requirements based on chosen plugins
https://github.com/elastic/windows-installers/issues/11
- [ ] Support configuration file as a PROPERTY
https://github.com/elastic/windows-installers/issues/46
- [ ] Change in xpack.{basic-feature}.enabled setting
https://github.com/elastic/elastic-stack-installers/issues/66