Fix options schema inconsistency for logLevel

[sergkop]

• This is a bugfix
• This is a code refactor
• This is a test update
• This is a typo fix
• This is a metadata update

For Bugs and Features; did you add new tests?

No

Motivation / Use-Case

I tried to use webpack-dev-server with {logLevel: 'silent'} option, but it fails with the following error

WebpackDevServerOptionsValidationError: Invalid configuration object. webpack-dev-server has been initialised using a configuration object that does not match the API schema.
 - configuration.logLevel should be one of these:
   "trace" | "debug" | "info" | "warn" | "error" | "none"

That happens because the options schema defines an incorrect 'none' value, while webpack-log expects the 'silent' value.

Breaking Changes

Additional Info

[jsf-clabot]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #1372 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1372   +/-   ##
=======================================
  Coverage   79.14%   79.14%           
=======================================
  Files           6        6           
  Lines         494      494           
  Branches      160      160           
=======================================
  Hits          391      391           
  Misses        103      103

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