feat(ejectPlugins): skip registering default plugins

[chimurai]

Description

• add ejectPlugins option

Motivation and Context

http-proxy-middleware is configured with some default plugins for common use cases.
Allow the proxy behaviour to be fully customised with ejectPlugins: true.

How has this been tested?

• docs
• unit tests

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[coveralls]

Coverage increased (+0.04%) to 97.039% when pulling 907abb2 on eject-plugins into 4bc66b9 on v3.