[BUG] Agent's image repository and tag are hardcoded

[starbops]

Describe the bug

virtbmc's image name and tag are hardcoded to starbops/virtbmc and dev no matter what KubeVirtBMC version is installed.

To Reproduce
Steps to reproduce the behavior:

1. Create a Kubernetes cluster
2. Install KubeVirt
3. Install cert-manager
4. Install KubeVirtBMC via make deploy
5. Create a virtual machine
6. The created virtbmc Pod will use the starbops/virtbmc:dev container image

Expected behavior

The image name and tag should follow the controller's by default and be configurable via the controller's flags to allow customization.

Screenshots

N/A

Environment (please complete the following information):

• OS: Harvester v1.3.2
• Kubernetes version: v1.28.12+rke2r1
• KubeVirt version: v1.1.1
• KubeVirtBMC version: v0.3.1

Additional context

First found in #19 (comment)

[starbops]

Close as fixed in #37 and #38.