Update dependency webpack-cli to v4

This MR contains the following updates:

Package	Type	Update	Change
webpack-cli	devDependencies	major	3.3.12 -> 4.1.0

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Release Notes

webpack/webpack-cli

v4.1.0

Compare Source

v4.0.0

Compare Source

Bug Fixes

• add compilation lifecycle in watch instance (#​1903) (02b6d21)
• cleanup package-utils package (#​1822) (fd5b92b)
• cli-executer supplies args further up (#​1904) (097564a)
• exit code for validation errors (59f6303)
• exit process in case of schema errors (71e89b4)

Features

• assign config paths in build dependencies in cache config (#​1900) (7e90f11)

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