Some CLI commands skip config validation

[oliversalzburg]

Describe the bug
Calling certain CLI commands can produce unexpected errors, because they skip config validation.

Stack trace

TypeError: Cannot destructure property 'className' of 'Configuration.PLATFORMS[this.options.type]' as it is undefined.
    at Configuration.initDriver (/home/oliver/projects/mikro-orm/packages/core/dist/utils/Configuration.js:160:21)
    at new Configuration (/home/oliver/projects/mikro-orm/packages/core/dist/utils/Configuration.js:26:28)
    at Function.getConfiguration (/home/oliver/projects/mikro-orm/packages/core/dist/utils/ConfigurationLoader.js:26:24)
    at async Object.handler (/home/oliver/projects/mikro-orm/packages/cli/dist/commands/GenerateCacheCommand.js:19:24)

To Reproduce
Steps to reproduce the behavior:

1. Create a mikro-orm.config.js with only module.exports = {};
2. Run mikro-orm cache:generate

Expected behavior
No unhandled errors.

Versions

Dependency	Version
node	16.6.2
typescript	4.3.5
mikro-orm	4.5.9
your-driver	postgres