[Controller] Only reconcile components if they are enabled (except Webservice, Sidekiq, Migrations)

Summary

Only reconciles components if they are enabled.

Closes #260 (closed)

Related to #164 (closed)

A separate MR will be created to address the option to disable Webservice, Sidekiq and Migrations. This MR primarily moves things around for readability and adds XEnabled methods, whereas changes to Webservice, Sidekiq, and Migrations will be a little more involved. This MR is big enough as it is, so separating the changes will make reviews a bit easier.

To do

General

• Split components out of gitlab_controller.go into their own files under controller/<component>.go
• Implement Enabled methods for all components
• Replace repeated calls to GetBoolValue in gitlab_controller.go with new Enabled methods

Support disabling components

Chart	Should	Can
Self-signed certs	y	y
Migrations	y	n - to be addressed in a separate MR
NGINX	y	y
Gitaly	y	y
MinIO	y	y
Redis	y	y
PostgreSQL	y	y
Pages	y	y
GitLab shell	y	y
Task-Runner	y	y
Exporter	n	y (I added support since the Chart supports disabling it, but we can revert that if we like
Webservice	y	n - to be addressed in a separate MR
Sidekiq	y	n - to be addressed in a separate MR
Registry	y	y