Next milestone: pm:enable should fail by default if hook_requirements() is not met

[codebymikey]

Is your feature request related to a problem? Please describe.

The solution implemented in #4733 currently attempts to maintain backwards compatibility by allowing invalid module installs to pass by default. Ideally, this shouldn't be the case.

Describe the solution you'd like
Switch the default behaviour so that the install fails by default, and a conscious decision must be made to bypass the installation requirements.

This change in behaviour should only be applied in the next major release.

Additional context
Further discussion is available in the original PR.