Remove `web` from the CLI command structure

[mikenikles]

With #247, we no longer need to accommodate for multiple services in the CLI command structure. We only had web for now and can get rid of that.

Tasks

• Merge Use the user's preferred package manager #256 first
• Update code and all directory structures
• Update docs

[mikenikles]

I have second thoughts on that... While web is the only category we currently have, I'm not sure it's worth the effort to remove it and make life harder if we decide to add it back later.

I could imagine additional core commands related to deployments, testing, etc that live in the CLI itself instead of separate plugins. In that case, we'll need web, as well as deployment, etc. categories.