Add schema validation

[ogonkov]

Please Read the CONTRIBUTING Guidelines
In particular the portion on Commit Message Formatting

Please check if the PR fulfills these requirements

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior? (You can also link to an open issue here)

Options is validated programmatically

What is the new behavior?

Options validated through schema, webpack will assist if given option is not match schema

Does this PR introduce a breaking change?

• Yes
• No

If this PR contains a breaking change, please describe the following...

• Impact:
• Migration path for existing applications:
• Github Issue(s) this is regarding:

Other information:
Closes #749

[JLHwung]

Thanks!

[ogonkov]

What should be done to get it merged @JLHwung ?

[JLHwung]

Hi @ogonkov, generally we have two-approval policy on merging PRs. Let's wait for a longer while. Thanks for your patience.

[ogonkov]

@JLHwung Can we invite someone here to review?

[nicolo-ribaudo]

Thanks!