Is your feature request related to a problem? Please describe.
In namespaces where resource quota have been set the solver pods often cannot be scheduled because the set limits have been reached.

Describe the solution you'd like
As of Kubernetes 1.12 resource quota can be set for specific priority classes. Adding support for setting the priority class to solver configurations would allow the pods to be scheduled without affecting or being affected by the limits for other objects in the same namespace.

Describe alternatives you've considered
Alternatively we looked at setting a different namespace for the solver, however this seems to be a topic of discussion considering the number of different issues and PRs around this.

Additional context
N/A

Environment details (if applicable):

• Kubernetes version (e.g. v1.10.2): v1.15.x, v1.16.x
• Cloud-provider/provisioner (e.g. GKE, kops AWS, etc): kops AWS/GCE
• cert-manager version (e.g. v0.4.0): v0.15.1
• Install method (e.g. helm or static manifests): helm

/kind feature