update: Support custom monitoring in cluster level

Created by: leoendless

Signed-off-by: leoliu leoliu@yunify.com

What type of PR is this?

/kind feature

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #

Special notes for reviewers: Related PRs: https://github.com/kubesphere/kubesphere/pull/3193 https://github.com/kubesphere/monitoring-dashboard/pull/8 https://github.com/kubesphere/ks-installer/pull/1225

Additional documentation, usage docs, etc.: