[stable/goldilocks] feat: add allow setting priority class

[barney71]

Why This PR?
With platform engineering it's important for infrastructure workloads to take precedence over user workloads when it comes to scheduling deployments. Defining priority classes comes to the rescue here.

Fixes #

Changes
Changes proposed in this pull request:

• introducing 2 new values
• introducing PriorityClass to controller and dashboard deployments

Checklist:

• [ x] I have included the name of the chart in the title of this PR in square brackets i.e. [stable/goldilocks].
• [x ] I have updated the chart version in Chart.yaml following Semantic Versioning.
• [ x] Any new values are backwards compatible and/or have sensible default.
• [x ] Any new values have been added to the README for the Chart, or helm-docs --sort-values-order=file has been run for the charts that support it.

[CLAassistant]

All committers have signed the CLA.

[barney71]

Hello Goldilocks team,
would someone please review this pr. Thanx.